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Dryptosaurus

2009-11-22T07:18:00.000-08:00

Dryptosaurus

Dryptosaurus Fossil range: Late Cretaceous, 70 Ma PreЄ Є O S D C P T J K Pg N ↓

Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Superfamily:	Tyrannosauroidea
Family:	Dryptosauridae Marsh, 1890
Genus:	Dryptosaurus Marsh, 1877
Species
D. aquilunguis (Cope, 1866) (type)

Dryptosaurus (from Greek Drypto, "tear" and Sauros, "lizard" ) was a genus of primitive tyrannosaur that lived in Eastern North America during the Maastrichtian stage of the Late Cretaceous period. A famous painting of the genus by Charles R. Knight has made it one of the more widely-known dinosaurs, in spite of its poor fossil record. Its specific name aquilunguis is Latin for "having claws like an eagle's".

Description

An early painting of Dryptosaurus aquilunguis by Charles R. Knight.

Illustrated fossil remains of Dryptosaurus aquilunguis.

Dryptosaurus was 6.5 m (20 feet) long, 1.8 m (6 feet) high at the hips, and weighed about 1.2 tons. Like its relative Eotyrannus, it had relatively long arms with three fingers. Each of these fingers was tipped by a talon-like 8 inch claw.^[1] These claws lend a meaning for the type species aquilunguis: eagle-clawed.

Discovery

In 1866, an incomplete skeleton (ANSP 9995) was found in New Jersey by workers in a quarry.^[1] Paleontologist E.D. Cope described the remains, naming the creature "Laelaps" ("storm wind", after the dog in Greek mythology that never failed to catch what it was hunting). "Laelaps" became one of the first dinosaurs described from North America (following Hadrosaurus, Aublysodon and Trachodon). Subsequently, it was discovered that the name "Laelaps" had already been given to a species of mite, and Cope's lifelong rival O.C. Marsh changed the name in 1877 to Dryptosaurus.

Classification

Before the discovery of Appalachiosaurus,^[2] it was classified in a number of theropod families. Originally considered a megalosaurid by Cope, it was later assigned to its own family (Dryptosauridae) by Marsh, and later found (through phylogenetic studied of the 1990s) to be a coelurosaur, though its exact placement within that group remained uncertain. The discovery of the closely related (and more complete) Appalachiosaurus made it clear that Dryptosaurus was a primitive tyrannosauroid.

The fossil material assigned to Dryptosaurus was reviewed by Ken Carpenter in 1997 in light of the many different theropods discovered since Cope's day. He felt that due to some unusual features it couldn't be placed in any existing family and warranted placement in its own family, Dryptosauridae.^[3] Dryptosaurus was the only large carnivore known in eastern North America before the discovery of Appalachiosaurus.

Paleoecology

An outdated historical depiction of Dryptosaurus confronting Elasmosaurus, with two Hadrosaurus in the background. By Cope, 1869.

Although certainly a carnivore, the paucity of known Cretaceous east coast dinosaurs make ascertaining the specific diet of Dryptosaurus difficult.^[1] Hadrosaurus and its relatives have been found in New Jersey as well, so they may have had a prominent part of its diet. Apart from hadrosaurids, nodosaurs were also present although less likely to be hunted due to their armor plating.

Ornithomimus

2009-11-22T07:17:00.000-08:00

Ornithomimus

Ornithomimus Fossil range: Late Cretaceous

Ornithomimus edmontonicus in "death pose", Royal Tyrrell Museum
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Family:	Ornithomimidae
Genus:	Ornithomimus Marsh, 1890
Species
O. velox (type) O. edmontonicus Sternberg, 1933
Synonyms
?Dromiceiomimus

Ornithomimus (pronounced /ˌɔrnɨθɵˈmaɪməs/ meaning 'bird mimic') is a genus of dinosaur from the Late Cretaceous Period of what is now North America. Ornithomimus velox was named on the basis of a foot and partial hand from the Maastrichtian Denver Formation, but better material has since been found in Canada, including the Edmontonian-age Ornithomimus edmontonicus and an excellent articulated specimen (species unknown) from Dinosaur Provincial Park. Other specimens assigned to Ornithomimus have been discovered on the Eastern Coast of the USA.

Description

Ornithomimus edmontonicus, Royal Ontario Museum.

Like other ornithomimids, Ornithomimus is characterized by a three-toed foot, long slender arms and a long neck with a birdlike skull. It differs from other ornithomimids, such as Struthiomimus, in having very slender, straight hand and foot claws and in having metacarpals and fingers of similar lengths.^[1] Its hands are remarkably sloth-like in appearance, which led Henry Fairfield Osborn to suggest that they were used to hook branches during feeding.

Ornithomimus was 12 ft (3.5 meters) long, 7 feet (2.10 meters) high and weighed around 100-150 kg. It was bipedal and superficially resembled an ostrich, except for its long tail. It would have been a swift runner.

In popular culture

Ornithomimus played a prominent role in the television series Prehistoric Park, where they were featured, to a greater or lesser extent, in every episode. They were portrayed as flock animals whose chicks have fluffy feathers and imprint on the first thing they see. They were also shown to have feeding habits more like that of a duck than an ostrich, a behavior based on an hypothesis (since refuted^[2]) which proposed that ornithomimids were filter feeders.^[3] Ornithomimus also appeared in a variety of motion pictures, including Fantasia (1940), The Valley of Gwangi (1969), Planet of Dinosaurs (1978) and the IMAX film T-Rex: Back to the Cretaceous (1998).

Dromaeosaurus

2009-11-22T07:16:00.000-08:00

Dromaeosaurus

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Dromaeosaurus Fossil range: Late Cretaceous, 76.5–74.8 Ma PreЄ Є O S D C P T J K Pg N ↓

Skull cast
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Family:	Dromaeosauridae
Subfamily:	Dromaeosaurinae
Genus:	Dromaeosaurus Matthew & Brown, 1922
Species
D. albertensis (type)

Dromaeosaurus (pronounced /ˌdrɒmiː.ɵˈsɔrəs/) was a genus of theropod dinosaur which lived during the Late Cretaceous period (middle late Campanian), sometime between 76.5 and 74.8 million years ago, in the western United States and Alberta, Canada. The name means 'running lizard' and is derived from the Greek dromeus (δρομευς) meaning 'runner' and sauros (σαυρος) meaning 'lizard'.

Description

Restoration

Dromaeosaurus was a small carnivore, the size of a wolf, about 2 m (6 ft) in length and 15 kg (33 lb) in weight. Its mouth was full of sharp teeth, and it had a sharp "sickle claw" on each foot.

Although only a few bones are known from the hindlimb, they indicate that Dromaeosaurus was a powerfully built animal. The presence of feathers in closely related animals makes it extremely likely that it was feathered as well.

Dromaeosaurus had remarkably large eyes and excellent vision. It also probably had a good sense of smell and hearing. Its neck was curved flexible and its jaws were solidly built. The tail was flexible at the base but sheathed in a lattice of bony rods; this allowed it to be carried in a sharply upturned position.

Discovery and later findings

Skeleton cast

Despite receiving widespread attention in popular books on dinosaurs, and the usage of a complete mounted skeleton cast in museums throughout the world, Dromaeosaurus is surprisingly poorly known from actual fossils. The preparation of the popular cast by the Tyrrell Museum was only made possible by knowledge gained from other dromaeosaurids that have been discovered more recently.

The first known Dromaeosaurus remains were discovered by paleontologist Barnum Brown during a 1914 expedition to Red Deer River on behalf of the American Museum of Natural History.^[1] The area where these bones were collected is now part of Dinosaur Provincial Park in Alberta, Canada.^[2] The find consisted of a partial skull 24 cm (9.4 in) in length, and some foot bones.^[1]^[2] Several other skull fragments, and about 30 isolated teeth, are known from subsequent discoveries in Alberta and Montana.^[2]

Several species of Dromaeosaurus have been described, but Dromaeosaurus albertensis is the most complete specimen.^[2] Additionally, it is apparent that this genus is even rarer than other small theropods, although it was one of the first small theropods described based on reasonably good cranial material.^[2]

Matthew and Brown originally placed Dromaeosaurus within "Deinodontidae" (now known as Tyrannosauridae), based on some similarities in the general proportions of the skull.^[1] In 1969, John H. Ostrom recognized that Dromaeosaurus shared many features with Velociraptor and the newly-discovered Deinonychus, and assigned these forms to a new family: Dromaeosauridae.^[3] Since then, many new relatives of Dromaeosaurus have been found.

Paleobiology and diet

Foot

Dromaeosaurus differs from most of its relatives in having a short, massive skull, a deep mandible, and robust teeth. The teeth tend to be more heavily worn than those of its relative Saurornitholestes, suggesting that its jaws were used for crushing and tearing rather than simply slicing through flesh. Therrien et al. (2005) estimated that Dromaeosaurus had a bite nearly three times as powerful as that of Velociraptor.^[4]

It is possible that Dromaeosaurus was more of a scavenger than other small theropods, or it may be that Dromaeosaurus relied more heavily on its jaws to dispatch its prey. It was probably better suited to tackling large prey than the more lightly built Saurornitholestes.

Relationships

The relationships of Dromaeosaurus are unclear. Although its rugged build gives it a primitive appearance, it was actually a very specialized animal.^[5] It is usually given its own subfamily, the Dromaeosaurinae; this group is thought to include Utahraptor, Achillobator, Adasaurus and perhaps Deinonychus.

However, the relationships of dromaeosaurs are still in a state of flux. "Dromaeosaurus Morphotype A" is the designation given to a series of unusual, ridged dromaeosaur teeth from Alberta. These teeth probably do not belong to Dromaeosaurus, although it is unclear from what animal they do come.

In popular culture

Dromaeosaurus are featured in Walking with Dinosaurs, stalking juvenile Torosaurus and attempting to steal eggs from Tyrannosaurus, despite never coexisting with the latter in real life. Dromaeosaurus makes an appearance in Jurassic Fight Club, where a pack is shown being capable of taking down Edmontosaurus in spite of the carnivores' small size, but the carcass is later taken by a Tyrannosaurus (despite the tyrannosaur not being contemporaneous with Dromaeosaurus).

Paronychodon

2009-11-22T07:15:00.000-08:00

Paronychodon

Paronychodon Fossil range: Late Cretaceous
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Superorder:	Dinosauria
Suborder:	Theropoda
Infraorder:	Coelurosauria
Genus:	Paronychodon
Species:	P. lacustris
Binomial name
*Paronychodon lacustris* Cope, 1876
Synonyms
?Zapsalis abradens ^{Cope, 1876}

Paronychodon (meaning "beside claw tooth") was a theropod dinosaur genus. It lived during the Late Cretaceous in what is now Montana. This genus is a tooth taxon.

The type species, discovered by Edward Drinker Cope in 1876, is Paronychodon lacustris. It is considered dubious because of the fragmentary nature of the fossils.

References

Coelurosauria

Troodon

2009-11-22T07:14:00.000-08:00

Troodon

Troodon Fossil range: Late Cretaceous, 75–65 Ma PreЄ Є O S D C P T J K Pg N

Restoration of Troodon preying on an insect
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Family:	Troodontidae
Genus:	Troodon Leidy, 1856
Species
T. formosus Leidy, 1856
Synonyms
Pectinodon Carpenter, 1982 Polydontosaurus Gilmore, 1932 Stenonychosaurus Sternberg, 1932

Troodon (or Troödon in older sources) is a genus of relatively small, bird-like dinosaur from the Late Cretaceous period (75-65 mya). Discovered in 1855, it was among the first dinosaurs found in North America.

Its name (pronounced /ˈtroʊ.ɵdɒn/ TROE-o-don) is Greek for "wounding tooth", referring to the dinosaur's teeth, which are different from those of most other theropods. The teeth bear prominent, apically oriented serrations. These "wounding" serrations, however, are morphometrically more similar to those of herbivorous reptiles, and suggest a possibly omnivorous diet.^[1]

Characteristics

Troodon was a small dinosaur, around 2 metres (6.6 ft) in length, 1 metre (3.3 ft) tall, and weighed about 27 to 45 kilograms (60 to 99 lb).^[2] It had very long, slender limbs, suggesting that the animal was able to move quickly. It had long 'arms' that folded against the wall of the thorax like a bird's. It had large, retractable sickle-shaped claws on its second toes, which were raised off the ground when running.

Because of these features scientists regard Troodon as a member of the Maniraptora. Its eyes were large (perhaps suggesting nocturnal activity) and slightly forward facing, giving Troodon some depth perception. In fact most reconstructions give Troodon eyes which point in a more forwards direction than almost any other dinosaur, which implies that it had better binocular vision than most dinosaurs. Their light skulls contained a capsule similar to those found in ostrich dinosaurs.

Troodon had one of the largest known brains of any dinosaur, relative to its body mass^[2] (comparable to modern birds). Hence it is believed to have been one of the most intelligent dinosaurs, even more intelligent than mammals of that era.^{[citation needed]}

Distribution

Troodon is known from the Judith River Formation and the upper Two Medicine Formation of Montana, the Judith River Group of Alberta, the Horseshoe Canyon Formation of Alberta, the North Slope of Alaska, and in the famous Lance and Hell Creek Formations of the USA. There is some evidence that Troodon favored cooler climates, as it seems to have been particularly abundant in northern areas and during cooler intervals, such as the Early Maastrichtian.

It seems unlikely that all of these fossils, which come from localities hundreds or thousands of miles apart, separated by millions of years of time, represent a single species of Troodon. However, further study and more fossils are needed to determine how many species of Troodon existed.

Paleobiology

Troodon is thought to have been a predator like other theropods. This view is supported by its Maniraptoran features (sickle claw on foot) and apparently good binocular vision.

Troodon teeth, however, are different from most other theropods. One comparative study of the feeding apparatus suggests that Troodon could have been an omnivore.^[1] The jaws met in a broad, U-shaped symphysis similar to that of an iguana, a lizard species adapted to a plant-eating lifestyle. Additionally, the teeth of Troodon bore large serrations each of which is called a denticle. There are pits at the intersections of the denticles, and the points of the denticles point towards the tip, or apex, of each tooth. The teeth show wear facets on their sides. Holtz (1998) also noted that characteristics used to support a predatory habit for Troodon - the grasping hands, large brain and stereoscopic vision, are all characteristics shared with the herbivorous/omnivorous primates and omnivorous Procyon (raccoon).

One study was based on the many Troodon teeth that have been collected from Late Cretaceous deposits from northern Alaska. These teeth are much larger than those collected from more southern sites, providing evidence that northern Alaskan populations of Troodon grew to larger average body size. The study suggests that the Alaskan Troodons may have had access to large animals as prey because there were no tyrannosaurids in their habitat to provide competition for those resources. This study also provides an analysis of the proportions and wear patterns of a large sample of Troodon teeth. It proposes that the wear patterns of all Troodon teeth suggest a diet of soft foods - inconsistent with bone chewing, invertebrate exoskeletons, or tough plant items. This study hypothesizes a diet primarily consisting of meat^[3]

Age determination studies performed on the fossilized remains of Troodon using growth ring counts suggest that the longevity of this dinosaur was around 3–5 years.^[4]

Reproduction

A clutch of Troodon formosus eggs partly encased in matrix. Museum of the Rockies specimen on loan to the Burke Museum. Photographed at Dinoday 2009.

Varriccho et al. (2002) have described eight Troodon nests. All of these nests are from the Two Medicine Formation of Montana. These are all in the collection of the Museum of the Rockies and their accession numbers are MOR 246, 299, 393, 675, 676, 750, 963, 1139. The first of these were discovered by John Horner in 1983. Horner (1984) found isolated bones and partial skeletons of the hypsilophodont Orodromeus very near the nests in the same horizon and described the eggs as those of Orodromeus.^[5] Horner and Weishampel (1996) reexamined the embryos preserved in the eggs and determined that they were those of Troodon, not Orodromeus.^[6]

Varricchio et al. (1997) made this determination with even more certainty when they described a partial skeleton of an adult Troodon (MOR 748) in contact with a clutch of at least five eggs (MOR 750), probably in a brooding position.^[7]

Varricchio et al. (1997) described the exact structure of Troodon nests. They were built from sediments, they were dish shaped, about 100 cm in internal diameter, and with a pronounced raised rim encircling the eggs. The more complete nests had between 16 (minimum number in MOR 246) and 24 (MOR 963) eggs. The eggs are shaped like elongated teardrops, with the more tapered ends pointed downwards and imbedded about halfway in the sediment. The eggs are pitched at an angle so that, on average, the upper half is closer to the center of the nest. There is no evidence that plant matter was present in the nest.

Varricchio et al.(1997) were able to extract enough evidence from the nests to infer several characteristics of Troodon reproductive biology. The results are that Troodon appears to have a type of reproduction that is intermediate between crocodiles and birds, as phylogeny would predict. The eggs are statistically grouped in pairs, which suggests that the animal had two functional oviducts, like crocodiles, rather than one, as in birds. Crocodiles lay many eggs that are small proportional to adult body size. Birds lay fewer, larger, eggs. Troodon was intermediate, laying an egg of about 0.5 kg for a 50 kg adult. This is 10 times larger than reptiles of the same mass, but two Troodon eggs are roughly equivalent to the 1.1 kg egg predicted for a 50 kg bird.

Varricchio et al. also found evidence for iterative laying, where the adult might lay a pair of eggs every one or two days, and then ensured simultaneous hatching by delaying brooding until all eggs were laid. MOR 363 was found with 22 empty (hatched) eggs, and the embryos found in the eggs of MOR 246 were in very similar states of development, implying that all of the young hatched simultaneously. The embryos had an advanced degree of skeletal development, implying that they were precocial or even superprecocial. The authors estimated 45 to 65 total days of adult nest attendance for laying, brooding, and hatching. The authors found no evidence that the young remained in the nest after hatching and suggested that, instead, they dispersed like hatchling crocodiles or megapode birds.^[8]

Varricchio et al. (2008) examined the bone histology of Troodon specimen MOR 748 and found that it lacked the bone resorption patterns that would indicate it was an egg-laying female. They also measured the ratio of the total volume of eggs in Troodon clutches to the body mass of the adult. They graphed correlations between this ratio and the type of parenting strategies used by extant birds and crocodiles and found that the ratio in Troodon was consistent with that in birds where only the adult male broods the eggs. From this they concluded that Troodon females likely did not brood eggs, that the males did, and this may be a character shared between maniraptoran dinosaurs and basal birds.^[9]

History

Troodon was originally spelled Troödon (with a diaeresis) by Joseph Leidy in 1856, which was officially amended to its current status by Sauvage in 1876.

The original tooth

The Troodon tooth was originally classified as a "lacertian" (lizard) by Leidy, but re-assigned as a megalosaurid dinosaur by Nopsca in 1901 (Megalosauridae having historically been a wastebin taxon for most carnivorous dinosaurs). In 1924, Gilmore suggested that the tooth belonged to the herbivorous pachycephalosaur Stegoceras, and that Stegoceras was in fact a junior synonym of Troodon (the similarity of troodontid teeth to those of herbivorous dinosaurs continues to lead many paleontologists to believe that these animals were omnivores). In 1945, Charles Mortram Sternberg rejected the possibility that Troodon was a pachycephalosaur due to its stronger similarity to the teeth of other carnivorous dinosaurs.

The first specimen of Troodon that was not a tooth, then referred to its own genus (Stenonychosaurus), was named by Sternberg in 1932, based on a foot, fragments of a hand, and some caudal vertebrae from Alberta. A remarkable feature of these remains was the enlarged claw on the second toe, which is now recognized as characteristic of Deinonychosauria. Sternberg initially classified Stenonychosaurus as a member of the family Coeluridae. Later, Sternberg (1951) speculated that since Stenonychosaurus had a "very peculiar pes" and Troodon "equally unusual teeth", they may be closely related. Unfortunately, no comparable specimens were available at that time to test the idea.

Head and neck of Dale Russell's Troodon sculpture, from the Natural History Museum, London.

A more complete skeleton of Stenonychosaurus was described by Dale Russell in 1969, which eventually formed the scientific foundation for a famous life-sized sculpture of Stenonychosaurus accompanied by its fictional, human-like descendant, the "dinosauroid". Stenonychosaurus became a well-known theropod in the 1980s, when the feet and braincase were described in more detail. Phil Currie, reviewing the known Troodontidae in 1987, reclassified Stenonychosaurus inequalis as a junior synonym of Troodon formosus. This synonymy has been widely adopted by other paleontologists, and therefore all of the specimens once called Stenonychosaurus are now referred to as Troodon in the recent scientific literature.

Classification

The type specimen of Troodon has caused problems with classification, as the entire genus is based only on a single tooth from the Judith River Formation. Since the discovery of the original tooth, postcranial material from a related animal were given the name Stenonychosaurus. More complete remains of Stenonychosaurus convinced most paleontologists that it in fact was the same animal as the original tooth, so the name Stenonychosaurus was replaced with its senior synonym, Troodon. Other genera, including Polyodontosaurus and Pectinodon, have also been assigned to Troodon based on the assumption that this particular tooth type is limited to only a single type of dinosaur. For this reason, the future of the name Troodon itself is dubious—in similar situations, genera based on teeth have been abandoned in favor of names based on better remains. Familiar names like Deinodon and Trachodon have been abandoned in this way, and further research may require Troodon be replaced with Stenonychosaurus. In a chapter of the 2005 book Dinosaur Provincial Park, Phil Currie (one of the leading experts on North American troodontids) resurrects the type species of Stenonychosaurus (S. inequalis) within the genus Troodon as Troodon inequalis (Currie, 2005).

The "Dinosauroid"

A model of the hypothetical Dinosauroid, Dinosaur Museum, Dorchester

In 1982 paleontologist Dale Russell, curator of vertebrate fossils at the National Museum of Canada in Ottawa, conjectured a possible evolutionary path that might have been taken by Troodon had it not perished in the K/T extinction event 65 million years ago,^[10] suggesting that it could have evolved into intelligent beings similar in body plan to humans. Over geologic time, Russell noted that there had been a steady increase in the encephalization quotient or EQ (the relative brain weight when compared to other species with the same body weight) among the dinosaurs.^[10] Russell had discovered the first Troodontid skull, and noted that, while its EQ was low compared to humans, it was six times higher than that of other dinosaurs. If the trend in Troodon evolution had continued to the present, its brain case could by now measure 1,100 cm³; comparable to that of a human.^[10] Troodontids had semi-manipulative fingers, able to grasp and hold objects to a certain degree, and binocular vision.^[10]

Russell proposed that this Dinosauroid, like most dinosaurs of the troodontid family, would have had large eyes and three fingers on each hand, one of which would have been partially opposed. As with most modern reptiles (and birds), he conceived of its genitalia as internal. Russell speculated that it would have required a navel, as a placenta aids the development of a large brain case. However, it would not have possessed mammary glands, and would have fed its young, as birds do, on regurgitated food. He speculated that its language would have sounded somewhat like bird song.^[11]

Russell's thought experiment has been met with criticism from other paleontologists since the 1980s, many of whom point out that Russell's Dinosauroid is overly anthropomorphic. Gregory S. Paul (1988) and Thomas R. Holtz Jr., consider it "suspiciously human" (Paul, 1988) and argue that a large-brained, highly intelligent troodontid would retain a more standard theropod body plan, with a horizontal posture and long tail, and would probably manipulate objects with the snout and feet in the manner of a bird, rather than with human-like "hands".^[11]

In popular culture

Troodon is featured in ITV's Prehistoric Park in 2006, where it was portrayed as a highly intelligent scavenger. It was also shown in two episodes of Dinosaur Planet. In one, a pack of dwarf Troodon make "friends" with a Pyroraptor; in another, a pack of Troodon attack a flock of Orodromeus. Troodon was also featured in an episode of Animal Armageddon and was the focus of an episode of Paleoworld, called "Troodon: Dinosaur Genius". This episode also featured the Dinosauroid.

In fiction, Troodon feature prominently in the 1994 science-fiction novel End of an Era by Robert J. Sawyer, in which they are the preferred host vehicle for intelligent Martian viral invaders. Also, an intelligent saurian species very like the Troodon, called the saurs, appears in Ken MacLeod's "Engines of Light" series of books.

In the Star Trek novel First Frontier by Diane Carey and James Kirkland, several members of the Enterprise crew travel back in time and find that Troodon has rudimentary language and were well coordinated hunters. They also encounter evolved Troodons, called Clan Ru, from the future that were transplanted before the extinction by the Preservers and were sentient beings capable of warp travel.

In the children’s television show Dinosaur Train, the eponymous train is run by a Troodon.

In the Land Before Time series, two wise and philosophical Troodon make an appearance as mysterious, possibly space-faring dinosaurs called Rainbow-Faces.

Albertosaurus

2009-11-22T07:11:00.000-08:00

Albertosaurus

Albertosaurus Fossil range: 75–67.5 Ma PreЄ Є O S D C P T J K Pg N Late Cretaceous

Albertosaurus skeleton at the Royal Tyrrell Museum in Alberta
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Family:	Tyrannosauridae
Genus:	Albertosaurus Osborn, 1905
Species
A. sarcophagus (type) Osborn, 1905
Synonyms
?Gorgosaurus Lambe, 1914

Albertosaurus (pronounced /ælˌbɜrtɵˈsɔrəs/; meaning "Alberta lizard") is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period, more than 70 million years ago. The type species, A. sarcophagus, was restricted in range to the modern-day Canadian province of Alberta, after which the genus is named. Scientists disagree on the content of the genus, with some recognizing Gorgosaurus libratus as a second species.

As a tyrannosaurid, Albertosaurus was a bipedal predator with tiny, two-fingered hands and a massive head with dozens of large, sharp teeth. It may have been at the top of the food chain in its local ecosystem. Although relatively large for a theropod, Albertosaurus was much smaller than its more famous relative Tyrannosaurus, probably weighing less than 2 metric tons.

Fossils of more than thirty individuals have been recovered, providing scientists with a more detailed knowledge of Albertosaurus anatomy than is available for most other tyrannosaurids. The discovery of 22 individuals at one site provides evidence of pack behavior and allows studies of ontogeny and population biology which are impossible with lesser-known dinosaurs.

Description

Albertosaurus sarcophagus with a human for scale

Albertosaurus was smaller than the truly gigantic tyrannosaurids like Tarbosaurus and Tyrannosaurus. Typical adults measured up to 9 meters (30 ft) long,^[1]^[2] while rare individuals of great age could grow to over 10 meters (33 ft) in length.^[3] Several independent mass estimates, obtained by different methods, suggest that an adult Albertosaurus weighed between 1.3 tonnes (1.4 short tons)^[4] and 1.7 tonnes (1.9 tons).^[5]

The massive skull of Albertosaurus, perched on a short, S-shaped neck, was approximately 1 meter (3.3 ft) long in the largest adults.^[6] Wide openings in the skull (fenestrae) reduced the weight of the head while also providing space for muscle attachment and sensory organs. Its long jaws contained more than 60 banana-shaped teeth; larger tyrannosaurids possessed fewer teeth. Unlike most theropods, Albertosaurus and other tyrannosaurids were heterodont, with teeth of different forms depending on their position in the mouth. The premaxillary teeth at the tip of the upper jaw were much smaller than the rest, more closely packed, and D-shaped in cross section.^[2] Above the eyes were short bony crests that may have been brightly colored in life and used in courtship to attract a mate.^[7]

Skeleton at Maryland Science Center

All tyrannosaurids, including Albertosaurus, shared a similar body appearance. Typically for a theropod, Albertosaurus was bipedal and balanced the heavy head and torso with a long tail. However, tyrannosaurid forelimbs were extremely small for their body size and retained only two digits. The hind limbs were long and ended in a four-toed foot. The first digit, called the hallux, was short and only the other three contacted the ground, with the third (middle) digit longer than the rest.^[2] Albertosaurus may have been able to reach speeds of 25–30 miles per hour.^[7]

Classification and systematics

Cladogram of Tyrannosauridae highlighting the position of Albertosaurus

Tyrannosauridae

Tyrannosaurinae

Albertosaurinae

	Albertosaurus

	Gorgosaurus

Albertosaurus is a member of the theropod family Tyrannosauridae, in the subfamily Albertosaurinae. Its closest relative is the slightly older Gorgosaurus libratus (sometimes called Albertosaurus libratus; see below).^[8] These two species are the only described albertosaurines, although other undescribed species may exist.^[9] Thomas Holtz found Appalachiosaurus to be an albertosaurine in 2004,^[2] but his more recent unpublished work locates it just outside Tyrannosauridae,^[10] in agreement with other authors.^[11]

The other major subfamily of tyrannosaurids is the Tyrannosaurinae, including Daspletosaurus, Tarbosaurus and Tyrannosaurus. Compared with these robust tyrannosaurines, albertosaurines had slender builds, with proportionately smaller skulls and longer bones of the lower leg (tibia) and feet (metatarsals and phalanges).^[6]^[8]

Discovery and naming

Albertosaurus was named by Henry Fairfield Osborn in a very brief note at the end of his 1905 description of Tyrannosaurus rex. The name honors Alberta, the Canadian province in which the first remains were found. The generic name also incorporates the Greek term σαυρος/sauros ("lizard"), the most common suffix in dinosaur names. The type species is A. sarcophagus, which means "flesh-eater" and has the same etymology as the funeral container with which it shares its name: a combination of the Ancient Greek words σαρξ/sarx ("flesh") and Φαγειν/phagein ("to eat").^[12] More than thirty specimens of all ages are known to science.^[3]^[9]

Early discoveries

The Red Deer River near Drumheller, Alberta. Almost three-quarters of all Albertosaurus remains have been discovered alongside the river, in outcrops like the ones on either side of this picture.

The type specimen is a partial skull, collected in 1884 from an outcrop of the Horseshoe Canyon Formation alongside the Red Deer River in Alberta. This specimen and a smaller skull associated with some skeletal material were recovered by expeditions of the Geological Survey of Canada, led by the famous geologist Joseph B. Tyrrell. The two skulls were assigned to the preexisting species "Laelaps incrassatus" by Edward Drinker Cope in 1892,^[13] despite the fact that the name Laelaps was preoccupied by a genus of mite and had been changed to Dryptosaurus in 1877 by Othniel Charles Marsh. Cope refused to recognize the new name created by his archrival Marsh, so it fell to Lawrence Lambe to change "Laelaps incrassatus" to Dryptosaurus incrassatus when he described the remains in detail in 1904.^[14] Shortly later, Osborn pointed out that D. incrassatus was based on generic tyrannosaurid teeth, so the two Alberta skulls could not be confidently referred to that species. The Alberta skulls also differed markedly from the remains of D. aquilunguis, type species of Dryptosaurus, so Osborn created the new name Albertosaurus sarcophagus for them in 1905. He did not describe the remains in any great detail, citing Lambe's complete description the year before.^[12] Both specimens (CMN 5600 and 5601) are stored in the Canadian Museum of Nature in Ottawa.

Dry Island bonebed

In 1910, American paleontologist Barnum Brown uncovered the remains of a large group of Albertosaurus at another quarry alongside the Red Deer River. Because of the large number of bones and the limited time available, Brown's party did not collect every specimen, but made sure to collect remains from all of the individuals they could identify in the bonebed. Among the bones deposited in the American Museum of Natural History collections in New York City are seven sets of right metatarsals, along with two isolated toe bones that did not match any of the metatarsals in size. This indicated the presence of at least nine individuals in the quarry. The Royal Tyrrell Museum of Palaeontology rediscovered the bonebed in 1997 and resumed fieldwork at the site, which is now located inside Dry Island Buffalo Jump Provincial Park.^[15] Further excavation from 1997 to 2005 turned up the remains of 13 more individuals of various ages, including a diminutive two-year-old and a very old individual estimated at over 10 meters (33 ft) in length. None of these individuals are known from complete skeletons, and most are represented by remains in both museums.^[3]^[4]

Gorgosaurus libratus

Sub-adult Gorgosaurus specimen in "death pose", Royal Tyrrell Museum of Palaeontology

In 1913, paleontologist Charles H. Sternberg recovered another tyrannosaurid skeleton from the slightly older Dinosaur Park Formation in Alberta. Lawrence Lambe named this dinosaur Gorgosaurus libratus in 1914.^[16] Other specimens were later found in Alberta and Montana. Finding few differences to separate the two genera, Dale Russell declared the name Gorgosaurus a junior synonym of Albertosaurus, which had been named first, and G. libratus was renamed Albertosaurus libratus in 1970. This addition extended the temporal range of the genus Albertosaurus backwards by several million years and its geographic range southwards by hundreds of kilometers.^[1]

In 2003, Phil Currie compared several tyrannosaurid skulls and came to the conclusion that the two species are more distinct than previously thought. The decision to use one or two genera is rather arbitrary, as the two species are sister taxa, more closely related to each other than to any other species. Recognizing this, Currie nevertheless recommended that Albertosaurus and Gorgosaurus be retained as separate genera, as they are no more similar than Daspletosaurus and Tyrannosaurus, which are almost always separated. In addition, several albertosaurine specimens have been recovered from Alaska and New Mexico, and Currie suggested that the Albertosaurus-Gorgosaurus situation may be clarified once these are described fully.^[9] Most authors have followed Currie's recommendation,^[2]^[4]^[17] but some have not.^[11]

Other discoveries

William Parks described a new species, Albertosaurus arctunguis, based on a partial skeleton excavated near the Red Deer River in 1928,^[18] but this species has been considered identical to A. sarcophagus since 1970.^[1] Parks' specimen (ROM 807) is housed in the Royal Ontario Museum in Toronto. Six more skulls and skeletons have since been discovered in Alberta and are housed in various Canadian museums. Fossils have also been reported from the American states of Montana, New Mexico, and Wyoming, but these probably do not represent A. sarcophagus and may not even belong to the genus Albertosaurus.^[2]^[9]

Albertosaurus megagracilis was based on a small tyrannosaurid skeleton from the Hell Creek Formation of Montana.^[19] It was renamed Dinotyrannus in 1995,^[20] but is now thought to represent a juvenile Tyrannosaurus rex.^[6]

Paleobiology

Growth pattern

A graph showing the hypothesized growth curves (body mass versus age) of four tyrannosaurids, with Albertosaurus drawn in red^[4]

Most age categories of Albertosaurus are represented in the fossil record. Using bone histology, the age of an individual animal at the time of death can often be determined, allowing growth rates to be estimated and compared with other species. The youngest known Albertosaurus is a two-year-old discovered in the Dry Island bonebed, which would have weighed about 50 kilograms (110 lb) and measured slightly more than 2 meters (7 ft) in length. The 10 meter (33 ft) specimen from the same quarry is the oldest and largest known, at 28 years of age. When specimens of intermediate age and size are plotted on a graph, an S-shaped growth curve results, with the most rapid growth occurring in a four-year period ending around the sixteenth year of life, a pattern also seen in other tyrannosaurids. The growth rate during this phase was 122 kilograms (268 lb) per year, based on an adult 1.3 tonnes (1.4 short tons). Other studies have suggested higher adult weights; this would affect the magnitude of the growth rate but not the overall pattern. Tyrannosaurids similar in size to Albertosaurus had similar growth rates, although the much larger Tyrannosaurus rex grew almost five times faster (601 kilograms 1325 lb per year) at its peak.^[3] The end of the rapid growth phase suggests the onset of sexual maturity in Albertosaurus, although growth continued at a slower rate throughout the animals' lives.^[3]^[4] Sexual maturation while still actively growing appears to be a shared trait among small^[21] and large^[22] dinosaurs as well as in large mammals such as humans and elephants.^[22] This pattern of relatively early sexual maturation differs strikingly from the pattern in birds, which delay their sexual maturity until after they have finished growing.^[17]^[22]

Life history

Albertosaurus skeleton at the Redpath Museum, Montreal

Most known Albertosaurus individuals were aged 14 years or more at the time of death. Juvenile animals are rarely found as fossils for several reasons, mainly preservation bias, where the smaller bones of younger animals were less likely to preserved by fossilization than the larger bones of adults, and collection bias, where smaller fossils are less likely to be noticed by collectors in the field.^[23] Young Albertosaurus are relatively large for juvenile animals, but their remains are still rare in the fossil record compared with adults. It has been suggested that this phenomenon is a consequence of life history, rather than bias, and that fossils of juvenile Albertosaurus are rare because they simply did not die as often as adults did.^[3]

A hypothesis of Albertosaurus life history postulates that hatchlings died in large numbers, but have not been preserved in the fossil record due to their small size and fragile construction. After just two years, juveniles were larger than any other predator in the region aside from adult Albertosaurus, and more fleet of foot than most of their prey animals. This resulted in a dramatic decrease in their mortality rate and a corresponding rarity of fossil remains. Mortality rates doubled at age twelve, perhaps the result of the physiological demands of the rapid growth phase, and then doubled again with the onset of sexual maturity between the ages of fourteen and sixteen. This elevated mortality rate continued throughout adulthood, perhaps due to high physiological demands, stress and injuries received during intraspecific competition for mates and resources, and eventually, the ever-increasing effects of senescence. The higher mortality rate in adults may explain their more common preservation. Very large animals were rare because few individuals survived long enough to attain such sizes. High infant mortality rates, followed by reduced mortality among juveniles and a sudden increase in mortality after sexual maturity, with very few animals reaching maximum size, is a pattern observed in many modern large mammals, including elephants, African buffalo, and rhinoceros. The same pattern is also seen in other tyrannosaurids. The comparison with modern animals and other tyrannosaurids lends support to this life history hypothesis, but bias in the fossil record may still play a large role, especially since more than two-thirds of all Albertosaurus specimens are known from one locality.^[3]^[17]

Pack behavior

Albertosaurus models, Royal Tyrell Museum.

The Dry Island bonebed discovered by Barnum Brown and his crew contains the remains of 22 Albertosaurus, the most individuals found in one locality of any Cretaceous theropod, and the second-most of any large theropod dinosaur behind the Allosaurus assemblage at the Cleveland Lloyd Dinosaur Quarry in Utah. The group seems to be composed of one very old adult; eight adults between 17 and 23 years old; seven sub-adults undergoing their rapid growth phases at between 12 and 16 years old; and six juveniles between the ages of 2 and 11 years, who had not yet reached the growth phase.^[3]

The near-absence of herbivore remains and the similar state of preservation between the many individuals at the Albertosaurus bonebed quarry led Phil Currie to conclude that the locality was not a predator trap like the La Brea Tar Pits in California, and that all of the preserved animals died at the same time. Currie claims this as evidence of pack behavior.^[15] Other scientists are skeptical, observing that the animals may have been driven together by drought, flood or for other reasons.^[3]^[23]^[24]

There is abundant evidence for gregarious behavior among herbivorous dinosaurs, including ceratopsians and hadrosaurs.^[25] However, only rarely are so many dinosaurian predators found at the same site. Small theropods like Deinonychus,^[26] Coelophysis and Megapnosaurus (Syntarsus) rhodesiensis^[27] have been found in aggregations, as have larger predators like Allosaurus and Mapusaurus.^[28] There is some evidence of gregarious behavior in other tyrannosaurids as well. Fragmentary remains of smaller individuals were found alongside "Sue," the Tyrannosaurus mounted in the Field Museum of Natural History in Chicago, and a bonebed in the Two Medicine Formation of Montana contains at least three specimens of Daspletosaurus, preserved alongside several hadrosaurs.^[29] These findings may corroborate the evidence for social behavior in Albertosaurus, although some or all of the above localities may represent temporary or unnatural aggregations.^[15] Others have speculated that instead of social groups, at least some of these finds represent Komodo dragon-like mobbing of carcasses, where aggressive competition leads to some of the predators being killed and cannibalized.^[23]

Currie also offers speculation on the pack-hunting habits of Albertosaurus. The leg proportions of the smaller individuals were comparable to those of Ornithomimids, which were probably among the fastest dinosaurs. Younger Albertosaurus were probably equally fleet-footed, or at least faster than their prey. Currie hypothesized that the younger members of the pack may have been responsible for driving their prey towards the adults, who were larger and more powerful, but also slower.^[15] Juveniles may also have had different lifestyles than adults, filling predator niches between the enormous adults and the smaller contemporaneous theropods, the largest of which were two orders of magnitude smaller than adult Albertosaurus in mass.^[2] A similar situation is observed in modern Komodo dragons, with hatchlings beginning life as small insectivores before growing to become the dominant predators on their islands.^[30] However, as the preservation of behavior in the fossil record is exceedingly rare, these ideas cannot readily be tested.

Paleoecology

The Horseshoe Canyon Formation is exposed in its type section at Horseshoe Canyon, Alberta.

All identifiable fossils of Albertosaurus sarcophagus are known from the Horseshoe Canyon Formation in Alberta. This geologic formation dates to the early Maastrichtian stage of the Late Cretaceous Period, 73 to 70 Ma (million years ago). Immediately below this formation is the Bearpaw Shale, a marine formation representing a section of the Western Interior Seaway. The seaway was receding as the climate cooled and sea levels subsided towards the end of the Cretaceous, exposing land that had previously been underwater. It was not a smooth process, however, and the seaway would periodically rise to cover parts of the region throughout Horseshoe Canyon times before finally receding altogether in the years after. Due to the changing sea levels, many different environments are represented in the Horseshoe Canyon Formation, including offshore and near-shore marine habitats and coastal habitats like lagoons, estuaries and tidal flats. Numerous coal seams represent ancient peat swamps. Like most of the other vertebrate fossils from the formation, Albertosaurus remains are found in deposits laid down in the deltas and floodplains of large rivers during the later half of Horseshoe Canyon times.^[31]

The fauna of the Horseshoe Canyon Formation is well-known, as vertebrate fossils, including those of dinosaurs, are quite common. Sharks, rays, sturgeons, bowfins, gars and the gar-like Aspidorhynchus made up the fish fauna. Mammals included multituberculates and the marsupial Didelphodon. The saltwater plesiosaur Leurospondylus has been found in marine sediments in the Horseshoe Canyon, while freshwater environments were populated by turtles, Champsosaurus, and crocodilians like Leidyosuchus and Stangerochampsa. Dinosaurs dominate the fauna, especially hadrosaurs, which make up half of all dinosaurs known, including the genera Edmontosaurus, Saurolophus and Hypacrosaurus. Ceratopsians and ornithomimids were also very common, together making up another third of the known fauna. Along with much rarer Ankylosaurians and pachycephalosaurs, all of these animals would have been prey for a diverse array of carnivorous theropods, including troodontids, dromaeosaurids, and caenagnathids. Adult Albertosaurus were the apex predators in this environment, with intermediate niches possibly filled by juvenile albertosaurs.

Megalosaurus

2009-11-22T07:09:00.000-08:00

Megalosaurus

Megalosaurus Fossil range: Middle Jurassic, 166 Ma PreЄ Є O S D C P T J K Pg N ↓

Some of the known material of M. bucklandii on display at OU Museum of Natural History
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Family:	Megalosauridae
Genus:	Megalosaurus Buckland, 1824
Species
M. bucklandii Mantell, 1827 (type) ?M. cambrensis (Newton, 1899) = Zanclodon cambrensis

Megalosaurus (meaning "Great Lizard", from Greek, μεγαλο-/megalo- meaning 'big', 'tall' or 'great' and σαυρος/sauros meaning 'lizard') is a genus of large meat-eating theropod dinosaurs of the Middle Jurassic period (Bathonian stage, 166 million years ago) of Europe (Southern England, France, Portugal). It is significant as the first genus of dinosaur (outside of birds) to be described and named.

Discovery

"Scrotum humanum"

The cover of Robert Plot's Natural History of Oxfordshire, 1677 (right). Plot's illustration of the lower extremity of a Megalosaurus femur (left).

Megalosaurus was the first dinosaur to be described in the scientific literature. Part of a bone was recovered from a limestone quarry at Cornwell near Chipping Norton, Oxfordshire, England in 1676. The fragment was sent to Robert Plot, Professor of Chemistry at the University of Oxford and first curator of the Ashmolean Museum, who published a description in his Natural History of Oxfordshire in 1677. He correctly identified the bone as the lower extremity of the femur of a large animal and he recognized that it was too large to belong to any known species. He therefore concluded it to be the thigh bone of a giant human, such as those mentioned in the Bible. The bone has since been lost but the illustration is detailed enough to identify it clearly as the femur of a Megalosaurus.^[1]

The Cornwell bone was described again by Richard Brookes in 1763. He called it "Scrotum humanum," while comparing its appearance to a pair of human testicles. The label was not considered to be a proper Linnaean "name" for the animal in question at the time, and was not used in subsequent literature. Technically, though, the name was published after the advent of binomial nomenclature, and so if it was truly intended to represent the erection of a new genus it would have priority over Megalosaurus. However, the rules of the ICZN state that if a name falls into disuse for 50 years after publication, it is no longer in competition for priority. Therefore, the name Scrotum humanum would be a nomen oblitum, or "forgotten name" even if it had been a valid genus to begin with.^[2]

Buckland's research

Megalosaurus vertebra - OUMNH

More discoveries were made, starting in 1815, again at the Stonesfield quarry (currently considered part of the Taynton Limestone Formation, dating to the mid-Bathonian stage of the Jurassic Period).^[3] They were acquired by William Buckland, Professor of Geology at the University of Oxford and dean of Christ Church. He did not know to what animal the bones belonged but, in 1818, after the Napoleonic Wars, the French comparative anatomist Georges Cuvier visited Buckland in Oxford and realised that the bones belonged to a giant lizard-like creature. Buckland then published descriptions of the bones in Transactions of the Geological Society, in 1824 (Physician James Parkinson had described them in an article in 1822).

Engraving from William Buckland's "Notice on the Megalosaurus or great Fossil Lizard of Stonesfield", 1824. Caption reads "anterior extremity of the right lower jaw of the Megalosaurus from Stonesfield near Oxford".

By 1824, Buckland had a piece of a lower jaw with teeth, some vertebrae, and fragments of pelvis, scapula and hind limbs, probably not all from the same individual. Buckland identified the organism as being a giant animal related to the Sauria (lizards) and he placed it in the new genus Megalosaurus, estimating the animal to be 12 m long in life.^[4] In 1826, Ferdinand von Ritgen gave this dinosaur a complete binomial, Megalosaurus conybeari, which was not used by later authors and is now considered a nomen oblitum. A year later, in 1827, Gideon Mantell included Megalosaurus in his geological survey of southeastern England, and assigned the species its current binomial name, Megalosaurus bucklandii.^[5] It would not be until 1842 that Richard Owen coined the term 'dinosaur'.

In 1997, a famous group of fossilised footprints (ichnites) was found in a limestone quarry at Ardley, 20 km Northeast of Oxford, England. They were thought to have been made by Megalosaurus and possibly also some left by Cetiosaurus. There are replicas of some of these footprints, set across the lawn of Oxford University Museum of Natural History.

Description

Since those first finds, many other Megalosaurus bones have been recovered but still no complete skeleton has been found. Therefore, the details of its physical appearance cannot be certain.

Early reconstructions

Reconstruction of Megalosaurus and Pterodactylus by Samuel Griswold Goodrich from 1859. This is typical of early reconstructions in presenting Megalosaurus as a quadruped; modern reconstructions make it bipedal.

In 1852, Benjamin Waterhouse Hawkins was commissioned to a build a model of Megalosaurus for the exhibition of dinosaurs at the Crystal Palace, which is still there to this day. Early paleontologists, never having seen such a creature before, reconstructed it like the dragons of popular mythology, with a huge head and walking on all fours. It was not until the middle of the nineteenth century, when other theropods began to be discovered in North America, that a more accurate picture was developed. Some confusion still exists, for at one time (before classification of dinosaurs became the serious business it is today), all theropods from Europe were given the title Megalosaurus. Since then, these have mostly been reclassified but older papers can still cause confusion. For further confusion, the most reproduced anatomy diagram of a Megalosaurus' skeleton was produced before any vertebrae had been recovered. While drawing it, Friedrich von Huene of the University of Tübingen, Germany, instead used the backbones of Altispinax, a mysterious big theropod known from high-spined dorsal vertebrae and at times classified as a spinosaur. Hence, many later drawings, based on his original, show Megalosaurus with a deep spinal ridge or even a small sail, like that of Spinosaurus.

Modern reconstructions

In fact, Megalosaurus did have a relatively large head and the teeth were clearly that of a carnivore. However, the long tail would have balanced the body and head and so Megalosaurus is now restored as a bipedal beast—like all other theropods—about 9 meters in length. The structure of the cervical vertebrae suggests that its neck would have been very flexible. To support its weight of around one tonne, the legs were large and muscular. Like all theropods, it had three forward facing toes and a single reversed one. Although they had not reached the minuscule size of later theropods like Tyrannosaurus, the fore limbs of Megalosaurus were small and probably had three or four digits.

Modern restoration

Living in what is now Europe, during the Jurassic Period (181 to 169 million years ago), Megalosaurus may have hunted stegosaurs and sauropods. Repeated descriptions of Megalosaurus hunting Iguanodon (another of the earliest dinosaurs named) through the forests that then covered the continent are probably inaccurate, because Iguanodon skeletons are found in much younger Early Cretaceous formations. No fossils assignable to Megalosaurus have been discovered in Africa, contrary to some outdated dinosaur books.

Although Megalosaurus was a powerful carnivore and could probably have attacked even the largest sauropods, it is also likely that it gained some of its food by scavenging. That is not to detract from its prowess as a hunter (Tyrannosaurus probably did much the same). Efficiency was necessary to feed such a large body.

There is a good descriptive display of Megalosaurus and of the history of discovery, in the Oxford University Museum of Natural History.

Inaccurate attributions

At one time, Megalosaurus was a 'wastebasket genus', used to classify many different kinds of large theropods. Dilophosaurus [1], Eustreptospondylus [2], and Metriacanthosaurus [3] were all initially believed to be species of Megalosaurus. In recent years, the genus has been subject to extensive reconsideration and most of the extraneous species have been removed.

In popular media

Outdated reconstruction in Crystal Palace, London.

Megalosaurus has the distinction of being the first dinosaur to appear in any popular media. Charles Dickens's novel Bleak House begins with a description of fog, whose primordial character is emphasized by mention of Megalosaurus. It has made a variety of other appearances as well. A Megalosaurus was one of the main dinosaurs featured in John Brosnan's 1984 novel, Carnosaur though it was not featured in its film adaptation. In the TV Show Dinosaurs, Earl Sinclair, the father, is a Megalosaurus. It also appears in the Doctor Who book "The Last Dodo" by Jacqueline Rayner.

Gorgosaurus

2009-11-22T07:06:00.000-08:00

Gorgosaurus

Gorgosaurus Fossil range: Late Cretaceous, 77–74 Ma PreЄ Є O S D C P T J K Pg N ↓

Sub-adult Gorgosaurus specimen in "death pose", Royal Tyrrell Museum of Palaeontology
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Family:	Tyrannosauridae
Genus:	Gorgosaurus Lambe, 1914
Species
G. libratus (type) Lambe, 1914

Gorgosaurus (pronounced /ˌɡɔrɡɵˈsɔrəs/ GOR-go-SOR-əs, meaning "fierce lizard") is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period, between about 77 and 74 million years ago. Fossil remains have been found in the Canadian province of Alberta and possibly the U.S. state of Montana. Paleontologists recognize only the type species, G. libratus, although other species have been erroneously referred to the genus.

Like most known tyrannosaurids, Gorgosaurus was a bipedal predator weighing more than a metric ton as an adult; dozens of large, sharp teeth lined its jaws, while its two-fingered forelimbs were comparatively small. Gorgosaurus was most closely related to Albertosaurus, and more distantly related to the larger Tyrannosaurus. Gorgosaurus and Albertosaurus are extremely similar, distinguished mainly by subtle differences in the teeth and skull bones. Some experts consider G. libratus to be a species of Albertosaurus; this would make Gorgosaurus a junior synonym of that genus.

Gorgosaurus lived in a lush floodplain environment along the edge of an inland sea. An apex predator, it was at the top of the food chain, preying upon abundant ceratopsids and hadrosaurs. In some areas, Gorgosaurus coexisted with another tyrannosaurid, Daspletosaurus. Though these animals were roughly the same size, there is some evidence of niche differentiation between the two. Gorgosaurus is the best-represented tyrannosaurid in the fossil record, known from dozens of specimens. These plentiful remains have allowed scientists to investigate its ontogeny, life history and other aspects of its biology.

Description

Gorgosaurus libratus with a human for scale

Gorgosaurus was smaller than Tyrannosaurus or Tarbosaurus, closer in size to Albertosaurus and Daspletosaurus. Adults reached 8 or 9 meters (26 to 30 ft) from snout to tail.^[1]^[2] Paleontologists have estimated full-grown adults to weigh more than 2.4 tonnes (2.7 short tons).^[3] The largest known skull measures 99 centimeters (39 in) long, just slightly smaller than that of Daspletosaurus.^[1] As in other tyrannosaurids, the skull was large compared to its body size, although chambers within the skull bones and large openings (fenestrae) between bones reduced its weight. Albertosaurus and Gorgosaurus share proportionally longer and lower skulls than Daspletosaurus and other tyrannosaurids. The end of the snout was blunt, and the nasal and parietal bones were fused along the midline of the skull, as in all other members of the family. The eye socket was circular rather than oval or keyhole-shaped as in other tyrannosaurid genera. A tall crest rose from the lacrimal bone in front of each eye, similar to Albertosaurus and Daspletosaurus.^[2] Differences in the shape of bones surrounding the brain set Gorgosaurus apart from Albertosaurus.^[4]

Life restoration of Gorgosaurus

Gorgosaurus teeth were typical of all known tyrannosaurids. The eight premaxillary teeth at the front of the snout were smaller than the rest, closely packed and D-shaped in cross section. In Gorgosaurus, the first tooth in the maxilla was also shaped like the premaxillary teeth. The rest of the teeth were oval in cross section, rather than blade-like as in most other theropods.^[2] Along with the eight premaxillary teeth, Gorgosaurus had 26 to 30 maxillary teeth and 30 to 34 teeth in the dentary bones of the lower jaw. This number of teeth is similar to Albertosaurus and Daspletosaurus but is fewer than those of Tarbosaurus or Tyrannosaurus.^[5]

Gorgosaurus shared its general body plan with all other tyrannosaurids. Its massive head was perched on the end of an S-shaped neck. In contrast to its large head, its forelimbs were very small. The forelimbs had only two digits, although a third metacarpal is known in some specimens, the vestigial remains of the third digit seen in other theropods. Gorgosaurus had four digits on each hindlimb, including a small first toe (hallux) which did not contact the ground. Tyrannosaurid hindlimbs were long relative to overall body size compared with other theropods.^[2] The largest known Gorgosaurus femur measured 105 centimeters (41 in) long. In several smaller specimens of Gorgosaurus, the tibia was longer than the femur, a proportion typical of fast-running animals.^[1] The two bones were of equal length in the largest specimens.^[6] The long, heavy tail served as a counterweight to the head and torso and placed the center of gravity over the hips.^[2]

Classification and systematics

Cladogram of Tyrannosauridae highlighting the position of Gorgosaurus

Carr et al. 2005^[7]

Tyrannosauridae

Albertosaurinae

	Albertosaurus

	Gorgosaurus*

Tyrannosaurinae

void

Daspletosaurus

void	Tarbosaurus*

	Tyrannosaurus

*Note: Carr et al. regard Gorgosaurus libratus as a species of Albertosaurus and Tarbosaurus bataar as a species of Tyrannosaurus

Currie et al. 2003^[5]

Tyrannosauridae

Albertosaurinae

	Albertosaurus

	Gorgosaurus

Tyrannosaurinae

void

Daspletosaurus

void	Tarbosaurus

	Alioramus

void	Nanotyrannus

	Tyrannosaurus

Gorgosaurus is classified in the theropod subfamily Albertosaurinae within the family Tyrannosauridae. It is most closely related to the slightly younger Albertosaurus.^[5] These are the only two definite albertosaurine genera that have been described, although other undescribed species may exist.^[4] Appalachiosaurus was described as a basal tyrannosauroid just outside Tyrannosauridae,^[7] although American paleontologist Thomas Holtz published a phylogenetic analysis in 2004 which indicated it was an albertosaurine.^[2] More recent, unpublished work by Holtz agrees with the original assessment.^[8] All other tyrannosaurid genera, including Daspletosaurus, Tarbosaurus and Tyrannosaurus, are classified in the subfamily Tyrannosaurinae. Compared to the tyrannosaurines, albertosaurines had slender builds, with proportionately smaller, lower skulls and longer bones of the lower leg (tibia) and feet (metatarsals and phalanges).^[5]^[9]

The close similarities between Gorgosaurus libratus and Albertosaurus sarcophagus have led many experts to combine them into one genus over the years. Albertosaurus was named first, so by convention it is given priority over the name Gorgosaurus, which is sometimes considered its junior synonym. William Diller Matthew and Barnum Brown doubted the distinction of the two genera as early as 1922.^[10] Gorgosaurus libratus was formally reassigned to Albertosaurus (as Albertosaurus libratus) by Dale Russell in 1970,^[1] and many subsequent authors followed his lead.^[7]^[11] Combining the two greatly expands the geographical and chronological range of the genus Albertosaurus. Other experts maintain the two genera as separate.^[2] Canadian paleontologist Phil Currie claims there are as many anatomical differences between Albertosaurus and Gorgosaurus as there are between Daspletosaurus and Tyrannosaurus, which are almost always kept separate. He also notes that undescribed tyrannosaurids discovered in Alaska, New Mexico and elsewhere in North America may help clarify the situation.^[4]

Discovery and naming

Gorgosaurus libratus specimen (AMNH 5428)

Gorgosaurus libratus was first described by Lawrence Lambe in 1914.^[12]^[13] Its name is derived from the Greek γοργος/gorgos ("fierce" or "terrible") and σαυρος/saurus ("lizard").^[14] The type species is G. libratus; the specific epithet "balanced" is the past participle of the Latin verb librare, meaning "to balance".^[13]

The holotype of Gorgosaurus libratus (NMC 2120) is a nearly complete skeleton associated with a skull, discovered in 1913 by Charles M. Sternberg. This specimen was the first tyrannosaurid found with a complete hand.^[12] It was found in the Dinosaur Park Formation of Alberta and is housed in the Canadian Museum of Nature in Ottawa.^[4] Prospectors from the American Museum of Natural History in New York City were active along the Red Deer River in Alberta at the same time, collecting hundreds of spectacular dinosaur specimens, including four complete G. libratus skulls, three of which were associated with skeletons. Matthew and Brown described four of these specimens in 1923.^[6]

Type specimen of Gorgosaurus sternbergi (AMNH 5664), now recognized as a juvenile Gorgosaurus libratus

Matthew and Brown also described a fifth skeleton (AMNH 5664), which Charles H. Sternberg had collected in 1917 and sold to their museum. It was smaller than other Gorgosaurus specimens, with a lower, lighter skull and more elongate limb proportions. Many sutures between bones were unfused in this specimen as well. Matthew and Brown noted that these features were characteristic of juvenile tyrannosaurids, but still described it as the holotype of a new species, G. sternbergi.^[6] Today's paleontologists regard this specimen as a juvenile G. libratus.^[2]^[4] Dozens of other specimens have been excavated from the Dinosaur Park Formation and are housed in museums across the United States and Canada.^[1]^[4] G. libratus is the best-represented tyrannosaurid in the fossil record, known from a virtually complete growth series.^[2]^[15]

Gorgosaurus libratus specimen (AMNH 5458)

In 1856, Joseph Leidy described two tyrannosaurid premaxillary teeth from Montana. Although there was no indication of what the animal looked like, the teeth were large and robust, and Leidy gave them the name Deinodon.^[16] Matthew and Brown commented in 1922 that these teeth were indistinguishable from those of Gorgosaurus, but in the absence of skeletal remains of Deinodon, opted not to synonymize the two genera.^[10] Although Deinodon teeth are very similar to those of Gorgosaurus, tyrannosaurid teeth are extremely uniform, so it cannot be said for certain which animal they belonged to. Deinodon is regarded as a nomen dubium today.^[1]^[15] Several tyrannosaurid skeletons from the Judith River Formation of Montana probably belong to Gorgosaurus, although it remains uncertain whether they belong to G. libratus or a new species.^[4] One specimen from Montana (TCMI 2001.89.1), housed in the Children's Museum of Indianapolis, shows evidence of severe pathologies, including healed leg, rib, and vertebral fractures, osteomyelitis (infection) at the tip of the lower jaw resulting in permanent tooth loss, and possibly a brain tumor.^[17]^[18]

Misassigned species

Several species were incorrectly assigned to Gorgosaurus in the twentieth century. A complete skull of a small tyrannosaurid (CMNH 7541), found in the younger, late Maastrichtian-age Hell Creek Formation of Montana, was named Gorgosaurus lancensis by Charles Whitney Gilmore in 1946.^[19] This specimen was renamed Nanotyrannus by Bob Bakker and colleagues in 1988.^[20] Today, most paleontologists recognize Nanotyrannus as a juvenile Tyrannosaurus rex.^[2]^[15] Similarly, Evgeny Maleev created the names Gorgosaurus lancinator and Gorgosaurus novojilovi for two small tyrannosaurid specimens (PIN 553-1 and PIN 552-2) from the Nemegt Formation of Mongolia in 1955.^[21] Ken Carpenter renamed the smaller specimen Maleevosaurus novojilovi in 1992,^[22] but both are now considered juveniles of Tarbosaurus bataar.^[2]^[15]^[23]

Paleobiology

Coexistence with Daspletosaurus

Gorgosaurus attacking the hadrosaur Parasaurolophus

In the Dinosaur Park Formation, Gorgosaurus lived alongside a rarer species of the tyrannosaurine Daspletosaurus. This is one of the few examples of two tyrannosaur genera coexisting. Similar-sized predators in modern predator guilds are separated into different ecological niches by anatomical, behavioral or geographical differences that limit competition. Niche differentiation between the Dinosaur Park tyrannosaurids is not well-understood.^[24] In 1970, Dale Russell hypothesized the more common Gorgosaurus actively hunted fleet-footed hadrosaurs, while the rarer and more troublesome ceratopsians and ankylosaurians (horned and heavily armoured dinosaurs) were left to the more heavy-built Daspletosaurus.^[1] However, a specimen of Daspletosaurus (OTM 200) from the contemporaneous Two Medicine Formation of Montana preserves the digested remains of a juvenile hadrosaur in its gut region.^[25]

Unlike some other groups of dinosaurs, neither genus was more common at higher or lower elevations than the other.^[24] However, Gorgosaurus appears more common in northern formations like the Dinosaur Park, with species of Daspletosaurus more abundant to the south. The same pattern is seen in other groups of dinosaurs. Chasmosaurine ceratopsians and hadrosaurine hadrosaurs are also more common in the Two Medicine Formation of Montana and in southwestern North America during the Campanian, while centrosaurine and lambeosaurines dominate in northern latitudes. Holtz has suggested this pattern indicates shared ecological preferences between tyrannosaurines, chasmosaurines and hadrosaurines. At the end of the later Maastrichtian stage, tyrannosaurines like Tyrannosaurus rex, hadrosaurines like Edmontosaurus and chasmosaurines like Triceratops were widespread throughout western North America, while albertosaurines and centrosaurines went extinct, and lambeosaurines were rare.^[2]

Life history

A graph showing the hypothesized growth curves (body mass versus age) of four tyrannosaurids. Gorgosaurus is shown in blue. Based on Erickson et al. 2004.

Gregory Erickson and colleagues have studied the growth and life history of tyrannosaurids using bone histology, which can determine the age of a specimen when it died. A growth curve can be developed when the ages of various individuals are plotted against their sizes on a graph. Tyrannosaurids grew throughout their lives, but underwent tremendous growth spurts for about four years, after an extended juvenile phase. Sexual maturity may have ended this rapid growth phase, after which growth slowed down considerably in adult animals. Examining five Gorgosaurus specimens of various sizes, Erickson calculated a maximum growth rate of about 110 kilograms (50 lb) during the rapid growth phase, slower than in tyrannosaurines like Daspletosaurus and Tyrannosaurus, but comparable to Albertosaurus.^[26]

Gorgosaurus spent as much as half its life in the juvenile phase before ballooning up to near-maximum size in only a few years.^[26] This, along with the complete lack of predators intermediate in size between huge adult tyrannosaurids and other small theropods, suggests these niches may have been filled by juvenile tyrannosaurids. This is seen in modern Komodo dragons, where hatchlings start off as tree-dwelling insectivores and slowly mature into massive apex predators capable of taking down large vertebrates.^[2] Other tyrannosaurids, including Albertosaurus, have been found in aggregations that some have suggested to represent mixed-age packs, but there is no evidence of gregarious behavior in Gorgosaurus.^[27]^[28]

Paleoecology

Mounted Gorgosaurus skeleton with several bone injuries, from the "Dinosaur Mummy: CSI" exhibit at the HMNS

All known specimens of Gorgosaurus libratus have been recovered from the Dinosaur Park Formation in Alberta.^[4] This formation dates to the middle of the Campanian, between 76.5 and 74 million years ago.^[29] At this time, the area was a coastal plain along the western edge of the Western Interior Seaway, which divided North America in half. The Laramide Orogeny had begun uplifting the Rocky Mountains to the west, from which flowed great rivers that deposited eroded sediment in vast floodplains along the coast.^[30]^[31] The climate was subtropical with marked seasonality, and periodic droughts sometimes resulted in massive mortality among the great herds of dinosaurs, as represented in the numerous bonebed deposits preserved in the Dinosaur Park Formation. Conifers formed the forest canopy, while the understory plants consisted of ferns, tree ferns and angiosperms.^[32] Around 73 million years ago, the seaway began to expand, transgressing into areas formerly above sea level and drowning the Dinosaur Park ecosystem. This transgression, called the Bearpaw Sea, is recorded by the marine sediments of the massive Bearpaw Shale.^[31]

The Dinosaur Park Formation preserves a great wealth of vertebrate fossils. A wide variety of fish swam the rivers and estuaries, including gars, sturgeons, sharks and rays, among others. Frogs, salamanders, turtles, crocodilians and champsosaurs also dwelled in the aquatic habitats. Azhdarchid pterosaurs and neornithine birds like Apatornis flew overhead, while the enantiornithine bird Avisaurus lived on the ground alongside multituberculate, marsupial and placental mammals. A number of species of terrestrial lizards were also present, including whiptails, skinks, monitors and alligator lizards. Dinosaur fossils in particular are found with unrivaled abundance and diversity. Huge herds of ceratopsids roamed the floodplains alongside equally large groups of hadrosaurine and lambeosaurine hadrosaurs. Other herbivorous groups like ornithomimids, therizinosaurs, pachycephalosaurs, small ornithopods, nodosaurids and ankylosaurids were also represented. Small predatory dinosaurs like oviraptorosaurs, troodonts and dromaeosaurs hunted smaller prey than the huge tyrannosaurids, Daspletosaurus and Gorgosaurus, which were two orders of magnitude larger in mass.^[31] Intervening predatory niches may have been filled by young tyrannosaurids.

Aublysodon

2009-11-22T07:04:00.000-08:00

Aublysodon

Aublysodon Fossil range: Late Cretaceous
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Order:	Saurischia
Superfamily:	Tyrannosauroidea
Family:	Tyrannosauridae
Genus:	Aublysodon
Binomial name
*Aublysodon mirandus* Leidy, 1868

Aublysodon (uncertain derivation; perhaps "backwards-flowing tooth"?) is a carnivorous dinosaur taxon named by Joseph Leidy in 1868. It is a dubious name, since the type specimen consists only of an isolated premaxillary tooth, found in strata from the Late Cretaceous Period. This specimen is now lost. Identical teeth have been found in many US states, western Canada, and Asia.^[1]. These teeth almost certainly belong to a juvenile tyrannosaurine tyrannosaurid, but cannot be identified with any more specificity.

Discovery

In the mid and late 1800s (19th century) many dinosaur taxa were named for isolated teeth; such genera include Trachodon, Palaeoscincus, and Troodon. Even before the badlands of North America started revealing the bones of Tyrannosaurus, teeth turning up in many localities in the Western United States revealed the presence of large predatory dinosaurs.

Leidy named nonserrated premaxillary teeth Aublysodon in 1868. These specimens had been collected from the Judith River Badlands of Montana.^[1] This tooth-based taxon was a mystery for a long time since no further skeletal elements were found that could be assigned with certainty to the teeth.

Later findings

The first skeletal material referred to Aublysodon was a partial skull unearthed in Montana^[1] in the 1980s. The skull bore pointed teeth attached to a long narrow skull the length of an average human arm. First thought to be a juvenile Tyrannosaurus, then interpreted as a large dromaeosaurid, this "Jordan theropod" was later (2004) reinterpreted to be a juvenile tyrannosaurine by Thomas Carr and Tom Williamson.^[2]

Another partial skeleton from New Mexico was considered to represent Aublysodon, but later research by Thomas Carr and Tom Williamson (2004) has shown that it is probably referable to Daspletosaurus.^[2]

Most recently, in 2006, a near complete skeleton of a 5-6 meter long tyrannosaurid was collected by private collectors in the Judith River Formation of eastern Montana. Due to the lack of serrations on its premaxillary teeth, and the similarity of the low, long skull to the "Jordan theropod," this specimen has been referred to Aublysodon. The similarity of this specimen to the "Jordan theropod" and immature tyrannosaurines from Asia strongly indicates that this specimen is in fact a juvenile of Daspletosaurus or a related taxon.

Now that the type specimen of Aublysodon is missing, the name is invalid, and coupled with the presence of Aublysodon teeth in juvenile tyrannosaurines, the name is no longer considered to represent a real biological taxon.^[2]

Current status

Most paleontologists no longer recognize Aublysodon as a valid genus. It is now widely considered to be just a juvenile tyrannosaurine. The apparently unique morphological traits of a long, low snout, nonserrated teeth, and upturned dentary tip are characteristic of younger tyrannosaurines in general.

Species

Type:

Aublysodon mirandus Leidy, 1868 (including Ornithomimus mirandus and Deinodon horridus, in part); teeth only

Other Species:

A. amplus (Marsh, 1892) and
A. cristatus (Marsh, 1892) were at one stage included with A. mirandus, but have now been referred to the corresponding Stygivenator (=Tyrannosaurus rex) species.
A. explanatus (Cope, 1876/Hatcher, 1903); nomen dubium included with Paronychodon explanatus.
A. (= Deinodon) grandis (Marsh, 1890/von Huene, 1932); nomen dubium
A. (= Deinodon) horridus (Leidy, 1856/Cope, 1868); nomen dubium
A. (= Deinodon) lateralis (Cope, 1876); nomen dubium
A. huoyanshanensis (Dong, 1977/Paul, 1988); from Shanshanosaurus, now believed to be a juvenile Tarbosaurus bataar.
A. lancensis (Gilmore, 1946/Charig, 1967); included with Nanotyrannus lancensis.
A. lancinator (Maleev, 1955/Charig, 1967); = Tarbosaurus bataar.
The "Jordan theropod", from Montana, originally A. molnari (Paul, 1988), was made the type species for Stygivenator by Olshevsky in 1992, but appears to be a juvenile Tyrannosaurus rex.
A. novojilovi (Maleev, 1955/Charig, 1967) is considered to be a juvenile Tarbosaurus bataar.

Tyrannosaurus

2009-11-22T06:30:00.001-08:00

Tyrannosaurus

Tyrannosaurus Fossil range: Late Cretaceous, 68.5–65.5 Ma PreЄ Є O S D C P T J K Pg N ↓

Cast of a specimen nicnamed "Stan" (specimen BHI 3033), at Manchester Museum
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
(unranked):	Coelurosauria
Superfamily:	Tyrannosauroidea
Family:	Tyrannosauridae
Subfamily:	Tyrannosaurinae
Genus:	Tyrannosaurus Osborn, 1905
Species
T. rex (type) Osborn, 1905
Synonyms
Manospondylus Cope, 1892 Dynamosaurus Osborn, 1905 ?Nanotyrannus Bakker, Williams & Currie, 1988 Stygivenator Olshevsky, 1995 Dinotyrannus Olshevsky, 1995

Tyrannosaurus (pronounced /tɨˌrænɵˈsɔrəs/ or /taɪˌrænɵˈsɔrəs/, meaning 'tyrant lizard') was a genus of theropod dinosaur. The species Tyrannosaurus rex ('rex' meaning 'king' in Latin), commonly abbreviated to T. rex, is a fixture in popular culture. It lived throughout what is now western North America, with a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the last three million years of the Cretaceous Period, approximately 68 to 65 million years ago. It was among the last non-avian dinosaurs to exist prior to the Cretaceous–Tertiary extinction event.

Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to the large and powerful hindlimbs, Tyrannosaurus forelimbs were small, though unusually powerful for their size, and bore two clawed digits. Although other theropods rivaled or exceeded Tyrannosaurus rex in size, it was the largest known tyrannosaurid and one of the largest known land predators, measuring up to 13 metres (43 ft) in length,^[1] up to 4 metres (13 ft) tall at the hips,^[2] and up to 6.8 metric tons (7.5 short tons) in weight.^[3] By far the largest carnivore in its environment, Tyrannosaurus rex may have been an apex predator, preying upon hadrosaurs and ceratopsians, although some experts have suggested it was primarily a scavenger. The debate over Tyrannosaurus as apex predator or scavenger is among the longest running debates in paleontology.

More than 30 specimens of Tyrannosaurus rex have been identified, some of which are nearly complete skeletons. Soft tissue and proteins have been reported in at least one of these specimens. The abundance of fossil material has allowed significant research into many aspects of its biology, including life history and biomechanics. The feeding habits, physiology and potential speed of Tyrannosaurus rex are a few subjects of debate. Its taxonomy is also controversial, with some scientists considering Tarbosaurus bataar from Asia to represent a second species of Tyrannosaurus and others maintaining Tarbosaurus as a separate genus. Several other genera of North American tyrannosaurids have also been synonymized with Tyrannosaurus.

Description

Various specimens of Tyrannosaurus rex with a human for scale

Size comparison of selected giant theropod dinosaurs, Tyrannosaurus in purple.

Tyrannosaurus rex was one of the largest land carnivores of all time; the largest complete specimen, FMNH PR2081 ("Sue"), measured 12.8 metres (42 ft) long, and was 4.0 metres (13 ft) tall at the hips.^[2] Mass estimates have varied widely over the years, from more than 7.2 metric tons (7.9 short tons),^[4] to less than 4.5 metric tons (5.0 short tons),^[5]^[6] with most modern estimates ranging between 5.4 and 6.8 metric tons (6.0 and 7.5 short tons).^[3]^[7]^[8]^[9] Although Tyrannosaurus rex was larger than the well known Jurassic theropod Allosaurus, it was slightly smaller than Cretaceous carnivores Spinosaurus and Giganotosaurus.^[10]^[11]

The neck of Tyrannosaurus rex formed a natural S-shaped curve like that of other theropods, but was short and muscular to support the massive head. The forelimbs had only two clawed fingers,^[1] along with an additional small metacarpal representing the remnant of a third digit.^[12] In contrast the hind limbs were among the longest in proportion to body size of any theropod. The tail was heavy and long, sometimes containing over forty vertebrae, in order to balance the massive head and torso. To compensate for the immense bulk of the animal, many bones throughout the skeleton were hollow, reducing its weight without significant loss of strength.^[1]

The largest known Tyrannosaurus rex skulls measure up to 5 feet (1.5 m) in length.^[13] Large fenestrae (openings) in the skull reduced weight and provided areas for muscle attachment, as in all carnivorous theropods. But in other respects Tyrannosaurus’ skull was significantly different from those of large non-tyrannosauroid theropods. It was extremely wide at the rear but had a narrow snout, allowing unusually good binocular vision.^[14]^[15] The skull bones were massive and the nasals and some other bones were fused, preventing movement between them; but many were pneumatized (contained a "honeycomb" of tiny air spaces) which may have made the bones more flexible as well as lighter. These and other skull-strengthening features are part of the tyrannosaurid trend towards an increasingly powerful bite, which easily surpassed that of all non-tyrannosaurids.^[16]^[17]^[18] The tip of the upper jaw was U-shaped (most non-tyrannosauroid carnivores had V-shaped upper jaws), which increased the amount of tissue and bone a tyrannosaur could rip out with one bite, although it also increased the stresses on the front teeth.^[19]^[20]

Profile view of a Tyrannosaurus skull (AMNH 5027)

The teeth of Tyrannosaurus rex displayed marked heterodonty (differences in shape).^[1]^[21] The premaxillary teeth at the front of the upper jaw were closely packed, D-shaped in cross-section, had reinforcing ridges on the rear surface, were incisiform (their tips were chisel-like blades) and curved backwards. The D-shaped cross-section, reinforcing ridges and backwards curve reduced the risk that the teeth would snap when Tyrannosaurus bit and pulled. The remaining teeth were robust, like "lethal bananas" rather than daggers; more widely spaced and also had reinforcing ridges.^[22] Those in the upper jaw were larger than those in all but the rear of the lower jaw. The largest found so far is estimated to have been 30 centimetres (12 in) long including the root when the animal was alive, making it the largest tooth of any carnivorous dinosaur.^[2]

Classification

Tyrannosaurus rex head reconstruction at the Oxford University Museum of Natural History.

Tyrannosaurus is the type genus of the superfamily Tyrannosauroidea, the family Tyrannosauridae, and the subfamily Tyrannosaurinae; in other words it is the standard by which paleontologists decide whether to include other species in the same group. Other members of the tyrannosaurine subfamily include the North American Daspletosaurus and the Asian Tarbosaurus,^[23]^[24] both of which have occasionally been synonymized with Tyrannosaurus.^[20] Tyrannosaurids were once commonly thought to be descendants of earlier large theropods such as megalosaurs and carnosaurs, although more recently they were reclassified with the generally smaller coelurosaurs.^[19]

Life restoration of a Tyrannosaurus rex.

In 1955, Soviet paleontologist Evgeny Maleev named a new species, Tyrannosaurus bataar, from Mongolia.^[25] By 1965, this species had been renamed Tarbosaurus bataar.^[26] Despite the renaming, many phylogenetic analyses have found Tarbosaurus bataar to be the sister taxon of Tyrannosaurus rex,^[24] and it has often been considered an Asian species of Tyrannosaurus.^[19]^[27]^[28] A recent redescription of the skull of Tarbosaurus bataar has shown that it was much narrower than that of Tyrannosaurus rex and that during a bite, the distribution of stress in the skull would have been very different, closer to that of Alioramus, another Asian tyrannosaur.^[29] A related cladistic analysis found that Alioramus, not Tyrannosaurus, was the sister taxon of Tarbosaurus, which, if true, would suggest that Tarbosaurus and Tyrannosaurus should remain separate.^[23]

Other tyrannosaurid fossils found in the same formations as Tyrannosaurus rex were originally classified as separate taxa, including Aublysodon and Albertosaurus megagracilis,^[20] the latter being named Dinotyrannus megagracilis in 1995.^[30] However, these fossils are now universally considered to belong to juvenile Tyrannosaurus rex.^[31] A small but nearly complete skull from Montana, 60 centimetres (2.0 ft) long, may be an exception. This skull was originally classified as a species of Gorgosaurus (G. lancensis) by Charles W. Gilmore in 1946,^[32] but was later referred to a new genus, Nanotyrannus.^[33] Opinions remain divided on the validity of N. lancensis. Many paleontologists consider the skull to belong to a juvenile Tyrannosaurus rex.^[34] There are minor differences between the two species, including the higher number of teeth in N. lancensis, which lead some scientists to recommend keeping the two genera separate until further research or discoveries clarify the situation.^[24]^[35]

Manospondylus

Skull of Tyrannosaurus rex, type specimen at the Carnegie Museum of Natural History. This was heavily and inaccurately restored with plaster using Allosaurus as a model, and has since been disassembled.

The first fossil specimen which can be attributed to Tyrannosaurus rex consists of two partial vertebrae (one of which has been lost) found by Edward Drinker Cope in 1892 and described as Manospondylus gigas. Osborn recognized the similarity between M. gigas and Tyrannosaurus rex as early as 1917 but, due to the fragmentary nature of the Manospondylus vertebrae, he could not synonymize them conclusively.^[36]

In June 2000, the Black Hills Institute located the type locality of M. gigas in South Dakota and unearthed more tyrannosaur bones there. These were judged to represent further remains of the same individual, and to be identical to those of Tyrannosaurus rex. According to the rules of the International Code of Zoological Nomenclature (ICZN), the system that governs the scientific naming of animals, Manospondylus gigas should therefore have priority over Tyrannosaurus rex, because it was named first. However, the Fourth Edition of the ICZN, which took effect on 1 January 2000, states that "the prevailing usage must be maintained" when "the senior synonym or homonym has not been used as a valid name after 1899" and "the junior synonym or homonym has been used for a particular taxon, as its presumed valid name, in at least 25 works, published by at least 10 authors in the immediately preceding 50 years ..."^[37] Tyrannosaurus rex may qualify as the valid name under these conditions and would most likely be considered a nomen protectum ("protected name") under the ICZN if it was ever challenged, which it has not yet been. Manospondylus gigas would then be deemed a nomen oblitum ("forgotten name").^[38]

Paleobiology

Life history

A graph showing the hypothesized growth curves (body mass versus age) of four tyrannosaurids. Tyrannosaurus rex is drawn in black. Based on Erickson et al. 2004.

The identification of several specimens as juvenile Tyrannosaurus rex has allowed scientists to document ontogenetic changes in the species, estimate the lifespan, and determine how quickly the animals would have grown. The smallest known individual (LACM 28471, the "Jordan theropod") is estimated to have weighed only 29.9 kg (66 lb), while the largest, such as FMNH PR2081 ("Sue") most likely weighed over 5400 kg (6 short tons). Histologic analysis of Tyrannosaurus rex bones showed LACM 28471 had aged only 2 years when it died, while "Sue" was 28 years old, an age which may have been close to the maximum for the species.^[3]

Histology has also allowed the age of other specimens to be determined. Growth curves can be developed when the ages of different specimens are plotted on a graph along with their mass. A Tyrannosaurus rex growth curve is S-shaped, with juveniles remaining under 1800 kg (2 short tons) until approximately 14 years of age, when body size began to increase dramatically. During this rapid growth phase, a young Tyrannosaurus rex would gain an average of 600 kg (1,300 lb) a year for the next four years. At 18 years of age, the curve plateaus again, indicating that growth slowed dramatically. For example, only 600 kg (1,300 lb) separated the 28-year-old "Sue" from a 22-year-old Canadian specimen (RTMP 81.12.1).^[3] Another recent histological study performed by different workers corroborates these results, finding that rapid growth began to slow at around 16 years of age.^[39] This sudden change in growth rate may indicate physical maturity, a hypothesis which is supported by the discovery of medullary tissue in the femur of a 16 to 20-year-old Tyrannosaurus rex from Montana (MOR 1125, also known as "B-rex"). Medullary tissue is found only in female birds during ovulation, indicating that "B-rex" was of reproductive age.^[40] Further study indicates an age of 18 for this specimen.^[41] Other tyrannosaurids exhibit extremely similar growth curves, although with lower growth rates corresponding to their lower adult sizes.^[42]

Over half of the known Tyrannosaurus rex specimens appear to have died within six years of reaching sexual maturity, a pattern which is also seen in other tyrannosaurs and in some large, long-lived birds and mammals today. These species are characterized by high infant mortality rates, followed by relatively low mortality among juveniles. Mortality increases again following sexual maturity, partly due to the stresses of reproduction. One study suggests that the rarity of juvenile Tyrannosaurus rex fossils is due in part to low juvenile mortality rates; the animals were not dying in large numbers at these ages, and so were not often fossilized. However, this rarity may also be due to the incompleteness of the fossil record or to the bias of fossil collectors towards larger, more spectacular specimens.^[42]

Sexual dimorphism

Tyrannosaurus skeleton casts mounted in a mating position, Jurassic Museum of Asturias.

As the number of specimens increased, scientists began to analyze the variation between individuals and discovered what appeared to be two distinct body types, or morphs, similar to some other theropod species. As one of these morphs was more solidly built, it was termed the 'robust' morph while the other was termed 'gracile.' Several morphological differences associated with the two morphs were used to analyze sexual dimorphism in Tyrannosaurus rex, with the 'robust' morph usually suggested to be female. For example, the pelvis of several 'robust' specimens seemed to be wider, perhaps to allow the passage of eggs.^[43] It was also thought that the 'robust' morphology correlated with a reduced chevron on the first tail vertebra, also ostensibly to allow eggs to pass out of the reproductive tract, as had been erroneously reported for crocodiles.^[44]

In recent years, evidence for sexual dimorphism has been weakened. A 2005 study reported that previous claims of sexual dimorphism in crocodile chevron anatomy were in error, casting doubt on the existence of similar dimorphism between Tyrannosaurus rex genders.^[45] A full-sized chevron was discovered on the first tail vertebra of "Sue," an extremely robust individual, indicating that this feature could not be used to differentiate the two morphs anyway. As Tyrannosaurus rex specimens have been found from Saskatchewan to New Mexico, differences between individuals may be indicative of geographic variation rather than sexual dimorphism. The differences could also be age-related, with 'robust' individuals being older animals.^[1]

Only a single Tyrannosaurus rex specimen has been conclusively shown to belong to a specific gender. Examination of "B-rex" demonstrated the preservation of soft tissue within several bones. Some of this tissue has been identified as a medullary tissue, a specialized tissue grown only in modern birds as a source of calcium for the production of eggshell during ovulation. As only female birds lay eggs, medullary tissue is only found naturally in females, although males are capable of producing it when injected with female reproductive hormones like estrogen. This strongly suggests that "B-rex" was female, and that she died during ovulation.^[40] Recent research has shown that medullary tissue is never found in crocodiles, which are thought to be the closest living relatives of dinosaurs, aside from birds. The shared presence of medullary tissue in birds and theropod dinosaurs is further evidence of the close evolutionary relationship between the two.^[46]

Posture

Outdated reconstruction (by Charles R. Knight), showing 'tripod' pose

Like many bipedal dinosaurs, Tyrannosaurus rex was historically depicted as a 'living tripod', with the body at 45 degrees or less from the vertical and the tail dragging along the ground, similar to a kangaroo. This concept dates from Joseph Leidy's 1865 reconstruction of Hadrosaurus, the first to depict a dinosaur in a bipedal posture.^[47] Henry Fairfield Osborn, former president of the American Museum of Natural History (AMNH) in New York City, who believed the creature stood upright, further reinforced the notion after unveiling the first complete Tyrannosaurus rex skeleton in 1915. It stood in this upright pose for nearly a century, until it was dismantled in 1992.^[48] By 1970, scientists realized this pose was incorrect and could not have been maintained by a living animal, as it would have resulted in the dislocation or weakening of several joints, including the hips and the articulation between the head and the spinal column.^[49] The inaccurate AMNH mount inspired similar depictions in many films and paintings (such as Rudolph Zallinger's famous mural The Age Of Reptiles in Yale University's Peabody Museum of Natural History)^[50] until the 1990s, when films such as Jurassic Park introduced a more accurate posture to the general public. Modern representations in museums, art, and film show Tyrannosaurus rex with its body approximately parallel to the ground and tail extended behind the body to balance the head.^[20]

Arms

Closeup of forelimb; specimen at National Museum of Natural History, Washington, DC.

Diagram illustrating Tyrannosaurus rex arm anatomy.

When Tyrannosaurus rex was first discovered, the humerus was the only element of the forelimb known.^[51] For the initial mounted skeleton as seen by the public in 1915, Osborn substituted longer, three-fingered forelimbs like those of Allosaurus.^[36] However, a year earlier, Lawrence Lambe described the short, two-fingered forelimbs of the closely related Gorgosaurus.^[52] This strongly suggested that Tyrannosaurus rex had similar forelimbs, but this hypothesis was not confirmed until the first complete Tyrannosaurus rex forelimbs were identified in 1989, belonging to MOR 555 (the "Wankel rex").^[53] The remains of "Sue" also include complete forelimbs.^[1] Tyrannosaurus rex arms are very small relative to overall body size, measuring only 1 metre (3.3 ft) long. However, they are not vestigial but instead show large areas for muscle attachment, indicating considerable strength. This was recognized as early as 1906 by Osborn, who speculated that the forelimbs may have been used to grasp a mate during copulation.^[54] It has also been suggested that the forelimbs were used to assist the animal in rising from a prone position.^[49] Another possibility is that the forelimbs held struggling prey while it was dispatched by the tyrannosaur's enormous jaws. This hypothesis may be supported by biomechanical analysis.

Bronze cast of the wishbone of "Sue", Field Museum

Tyrannosaurus rex forelimb bones exhibit extremely thick cortical bone, indicating that they were developed to withstand heavy loads. The biceps brachii muscle of a full-grown Tyrannosaurus rex was capable of lifting 199 kilograms (439 lb) by itself; this number would only increase with other muscles (like the brachialis) acting in concert with the biceps. A Tyrannosaurus rex forearm also had a reduced range of motion, with the shoulder and elbow joints allowing only 40 and 45 degrees of motion, respectively. In contrast, the same two joints in Deinonychus allow up to 88 and 130 degrees of motion, respectively, while a human arm can rotate 360 degrees at the shoulder and move through 165 degrees at the elbow. The heavy build of the arm bones, extreme strength of the muscles, and limited range of motion may indicate a system designed to hold fast despite the stresses of a struggling prey animal.^[55]

Soft tissue

In the March 2005 issue of Science, Mary Higby Schweitzer of North Carolina State University and colleagues announced the recovery of soft tissue from the marrow cavity of a fossilized leg bone, from a 68-million-year-old Tyrannosaurus. The bone had been intentionally, though reluctantly, broken for shipping and then not preserved in the normal manner, specifically because Schweitzer was hoping to test it for soft tissue.^[56] Designated as the Museum of the Rockies specimen 1125, or MOR 1125, the dinosaur was previously excavated from the Hell Creek Formation. Flexible, bifurcating blood vessels and fibrous but elastic bone matrix tissue were recognized. In addition, microstructures resembling blood cells were found inside the matrix and vessels. The structures bear resemblance to ostrich blood cells and vessels. Whether an unknown process, distinct from normal fossilization, preserved the material, or the material is original, the researchers do not know, and they are careful not to make any claims about preservation.^[57] If it is found to be original material, any surviving proteins may be used as a means of indirectly guessing some of the DNA content of the dinosaurs involved, because each protein is typically created by a specific gene. The absence of previous finds may merely be the result of people assuming preserved tissue was impossible, therefore simply not looking. Since the first, two more tyrannosaurs and a hadrosaur have also been found to have such tissue-like structures.^[56] Research on some of the tissues involved has suggested that birds are closer relatives to tyrannosaurs than other modern animals.^[58]

In studies reported in the journal Science in April 2007, Asara and colleagues concluded that seven traces of collagen proteins detected in purified Tyrannosaurus rex bone most closely match those reported in chickens, followed by frogs and newts. The discovery of proteins from a creature tens of millions of years old, along with similar traces the team found in a mastodon bone at least 160,000 years old, upends the conventional view of fossils and may shift paleontologists' focus from bone hunting to biochemistry. Until these finds, most scientists presumed that fossilization replaced all living tissue with inert minerals. Paleontologist Hans Larsson of McGill University in Montreal, who was not part of the studies, called the finds "a milestone", and suggested that dinosaurs could "enter the field of molecular biology and really slingshot paleontology into the modern world."^[59]

Subsequent studies in April 2008 confirmed the close connection of Tyrannosaurus rex to modern birds. Postdoctoral biology researcher Chris Organ at Harvard University announced, "With more data, they would probably be able to place T. rex on the evolutionary tree between alligators and chickens and ostriches." Co-author John M. Asara added, "We also show that it groups better with birds than modern reptiles, such as alligators and green anole lizards."^[60]

The presumed soft tissue was called into question by Thomas Kaye of the University of Washington and his co-authors in 2008. They contend that what was really inside the tyrannosaur bone was slimy biofilm created by bacteria that coated the voids once occupied by blood vessels and cells.^[61] The researchers found that what previously had been identified as remnants of blood cells, because of the presence of iron, were actually framboids, microscopic mineral spheres bearing iron. They found similar spheres in a variety of other fossils from various periods, including an ammonite. In the ammonite they found the spheres in a place where the iron they contain could not have had any relationship to the presence of blood.^[62]

Skin and feathers

Main article: Feathered dinosaurs

Restoration of Raptorex, a small, primitive tyrannosauroid that might have been covered with feathers

In 2004, the scientific journal Nature published a report describing an early tyrannosauroid, Dilong paradoxus, from the famous Yixian Formation of China. As with many other theropods discovered in the Yixian, the fossil skeleton was preserved with a coat of filamentous structures which are commonly recognized as the precursors of feathers. It has also been proposed that Tyrannosaurus and other closely related tyrannosaurids had such protofeathers. However, skin impressions from large tyrannosaurid specimens show mosaic scales.^[63] While it is possible that protofeathers existed on parts of the body which have not been preserved, a lack of insulatory body covering is consistent with modern multi-ton mammals such as elephants, hippopotamus, and most species of rhinoceros. As an object increases in size, its ability to retain heat increases due to its decreasing surface area-to-volume ratio. Therefore, as large animals evolve in or disperse into warm climates, a coat of fur or feathers loses its selective advantage for thermal insulation and can instead become a disadvantage, as the insulation traps excess heat inside the body, possibly overheating the animal. Protofeathers may also have been secondarily lost during the evolution of large tyrannosaurids like Tyrannosaurus, especially in warm Cretaceous climates.^[64]

Thermoregulation

Main article: Physiology of dinosaurs

Tyrannosaurus, like most dinosaurs, was long thought to have an ectothermic ("cold-blooded") reptilian metabolism. The idea of dinosaur ectothermy was challenged by scientists like Robert T. Bakker and John Ostrom in the early years of the "Dinosaur Renaissance", beginning in the late 1960s.^[65]^[66] Tyrannosaurus rex itself was claimed to have been endothermic ("warm-blooded"), implying a very active lifestyle.^[6] Since then, several paleontologists have sought to determine the ability of Tyrannosaurus to regulate its body temperature. Histological evidence of high growth rates in young Tyrannosaurus rex, comparable to those of mammals and birds, may support the hypothesis of a high metabolism. Growth curves indicate that, as in mammals and birds, Tyrannosaurus rex growth was limited mostly to immature animals, rather than the indeterminate growth seen in most other vertebrates.^[39]

Oxygen isotope ratios in fossilized bone are sometimes used to determine the temperature at which the bone was deposited, as the ratio between certain isotopes correlates with temperature. In one specimen, the isotope ratios in bones from different parts of the body indicated a temperature difference of no more than 4 to 5°C (7 to 9°F) between the vertebrae of the torso and the tibia of the lower leg. This small temperature range between the body core and the extremities was claimed by paleontologist Reese Barrick and geochemist William Showers to indicate that Tyrannosaurus rex maintained a constant internal body temperature (homeothermy) and that it enjoyed a metabolism somewhere between ectothermic reptiles and endothermic mammals.^[67] Other scientists have pointed out that the ratio of oxygen isotopes in the fossils today does not necessarily represent the same ratio in the distant past, and may have been altered during or after fossilization (diagenesis).^[68] Barrick and Showers have defended their conclusions in subsequent papers, finding similar results in another theropod dinosaur from a different continent and tens of millions of years earlier in time (Giganotosaurus).^[69] Ornithischian dinosaurs also showed evidence of homeothermy, while varanid lizards from the same formation did not.^[70] Even if Tyrannosaurus rex does exhibit evidence of homeothermy, it does not necessarily mean that it was endothermic. Such thermoregulation may also be explained by gigantothermy, as in some living sea turtles.^[71]^[72]

Footprints

The probable Tyrannosaurus rex footprint from New Mexico.

Two isolated fossilized footprints have been tentatively assigned to Tyrannosaurus rex. The first was discovered at Philmont Scout Ranch, New Mexico, in 1983 by American geologist Charles Pillmore. Originally thought to belong to a hadrosaurid, examination of the footprint revealed a large 'heel' unknown in ornithopod dinosaur tracks, and traces of what may have been a hallux, the dewclaw-like fourth digit of the tyrannosaur foot. The footprint was published as the ichnogenus Tyrannosauripus pillmorei in 1994, by Martin Lockley and Adrian Hunt. Lockley and Hunt suggested that it was very likely the track was made by a Tyrannosaurus rex, which would make it the first known footprint from this species. The track was made in what was once a vegetated wetland mud flat. It measures 83 centimetres (33 in) long by 71 centimetres (28 in) wide.^[73]

A second footprint that may have been made by a Tyrannosaurus was first reported in 2007 by British paleontologist Phil Manning, from the Hell Creek Formation of Montana. This second track measures 76 centimetres (30 in) long, shorter than the track described by Lockley and Hunt. Whether or not the track was made by Tyrannosaurus is unclear, though Tyrannosaurus and Nanotyrannus are the only large theropods known to have existed in the Hell Creek Formation. Further study of the track (a full description has not yet been published) will compare the Montana track with the one found in New Mexico.^[74]

Locomotion

A sequence of theropod footprints (Grallator). No such sequence has yet been reported for tyrannosaurs, making gait and speed estimates difficult.

There are two main issues concerning the locomotory abilities of Tyrannosaurus: how well it could turn; and what its maximum straight-line speed was likely to have been. Both are relevant to the debate about whether it was a hunter or a scavenger (see below).

Tyrannosaurus may have been slow to turn, possibly taking one to two seconds to turn only 45° — an amount that humans, being vertically oriented and tail-less, can spin in a fraction of a second.^[75] The cause of the difficulty is rotational inertia, since much of Tyrannosaurus’ mass was some distance from its center of gravity, like a human carrying a heavy timber — although it might have reduced the average distance by arching its back and tail and pulling its head and forelimbs close to its body, rather like the way ice skaters pull their arms closer in order to spin faster.^[76]

Scientists have produced a wide range of maximum speed estimates, mostly around 11 metres per second (40 km/h; 25 mph), but a few as low as 5–11 metres per second (18–40 km/h; 11–25 mph), and a few as high as 20 metres per second (72 km/h; 45 mph). Researchers have to rely on various estimating techniques because, while there are many tracks of very large theropods walking, so far none have been found of very large theropods running—and this absence may indicate that they did not run.^[77] Scientists who think that Tyrannosaurus was able to run point out that hollow bones and other features that would have lightened its body may have kept adult weight to a mere 5 short tons (4.5 t) or so, or that other animals like ostriches and horses with long, flexible legs are able to achieve high speeds through slower but longer strides. Additionally, some have argued that Tyrannosaurus had relatively larger leg muscles than any animal alive today, which could have enabled fast running 40–70 kilometres per hour (25–43 mph).^[78]

Jack Horner and Don Lessem argued in 1993 that Tyrannosaurus was slow and probably could not run (no airborne phase in mid-stride), because its ratio of femur (thigh bone) to tibia (shin bone) length was greater than 1, as in most large theropods and like a modern elephant.^[53] However, Holtz (1998) noted that tyrannosaurids and some closely related groups had significantly longer distal hindlimb components (shin plus foot plus toes) relative to the femur length than most other theropods), and that tyrannosaurids and their close relatives had a tightly interlocked metatarsus that more effectively transmitted locomotory forces from the foot to the lower leg than in earlier theropods ("metatarsus" means the foot bones, which function as part of the leg in digitigrade animals). He therefore concluded that tyrannosaurids and their close relatives were the fastest large theropods.^[79]

Femur (thigh bone)

Tibia (shin bone)

Metatarsals (foot bones)

Dewclaw

Phalanges (toe bones)

Skeletal anatomy of a T. rex right leg

Christiansen (1998) estimated that the leg bones of Tyrannosaurus were not significantly stronger than those of elephants, which are relatively limited in their top speed and never actually run (there is no airborne phase), and hence proposed that the dinosaur's maximum speed would have been about 11 metres per second (40 km/h; 25 mph), which is about the speed of a human sprinter. But he also noted that such estimates depend on many dubious assumptions.^[80]

Farlow and colleagues (1995) have argued that a Tyrannosaurus weighing 6 short tons (5.4 t) to 8 short tons (7.3 t) would have been critically or even fatally injured if it had fallen while moving quickly, since its torso would have slammed into the ground at a deceleration of 6 g (six times the acceleration due to gravity, or about 60 meters/s²) and its tiny arms could not have reduced the impact.^[7] However, giraffes have been known to gallop at 50 kilometres per hour (31 mph), despite the risk that they might break a leg or worse, which can be fatal even in a "safe" environment such as a zoo.^[81]^[82] Thus it is quite possible that Tyrannosaurus also moved fast when necessary and had to accept such risks.^[83]^[84]

Most recent research on Tyrannosaurus locomotion does not support speeds faster than 40 kilometres per hour (25 mph), i.e. moderate-speed running. For example, a 2002 paper in the journal Nature used a mathematical model (validated by applying it to three living animals, alligators, chickens, and humans; additionally later eight more species including emus and ostriches^[85]) to gauge the leg muscle mass needed for fast running (over 40 kilometres per hour (25 mph)).^[78] They found that proposed top speeds in excess of 40 kilometres per hour (25 mph) were unfeasible, because they would require very large leg muscles (more than approximately 40–86% of total body mass). Even moderately fast speeds would have required large leg muscles. This discussion is difficult to resolve, as it is unknown how large the leg muscles actually were in Tyrannosaurus. If they were smaller, only 18 kilometres per hour (11 mph) walking/jogging might have been possible.^[78]

A study in 2007 used computer models to estimate running speeds, based on data taken directly from fossils, and claimed that Tyrannosaurus rex had a top running speed of 8 metres per second (29 km/h; 18 mph). An average professional football (soccer) player would be slightly slower, while a human sprinter can reach 12 metres per second (43 km/h; 27 mph). Note that these computer models predict a top speed of 17.8 metres per second (64 km/h; 40 mph) for a 3-kilogram (6.6 lb) Compsognathus^[86]^[87] (probably a juvenile individual).^[88]

Those who argue that Tyrannosaurus was incapable of running estimate the top speed of Tyrannosaurus at about 17 kilometres per hour (11 mph). This is still faster than its most likely prey species, hadrosaurids and ceratopsians.^[78] In addition, some advocates of the idea that Tyrannosaurus was a predator claim that tyrannosaur running speed is not important, since it may have been slow but still faster than its probable prey.^[89] However, Paul and Christiansen (2000) argued that at least the later ceratopsians had upright forelimbs and the larger species may have been as fast as rhinos.^[90] Healed Tyrannosaurus bite wounds on ceratopsian fossils are interpreted as evidence of attacks on living ceratopsians (see below). If the ceratopsians that lived alongside Tyrannosaurus were fast, that casts doubt on the argument that Tyrannosaurus did not have to be fast to catch its prey.^[84]

Feeding strategies

The debate about whether Tyrannosaurus was a predator or a pure scavenger is as old as the debate about its locomotion. Lambe (1917) described a good skeleton of Tyrannosaurus’ close relative Gorgosaurus and concluded that it and therefore also Tyrannosaurus was a pure scavenger, because the Gorgosaurus’ teeth showed hardly any wear.^[91] This argument is no longer taken seriously, because theropods replaced their teeth quite rapidly. Ever since the first discovery of Tyrannosaurus most scientists have agreed that it was a predator, although like modern large predators it would have been happy to scavenge or steal another predator's kill if it had the opportunity.^[92]

Noted hadrosaur expert Jack Horner is currently the major advocate of the idea that Tyrannosaurus was exclusively a scavenger and did not engage in active hunting at all.^[53]^[93]^[94] Horner has presented several arguments to support the pure scavenger hypothesis:

Cast of a Tyrannosaurus rex braincase at the Australian Museum, Sydney.

Tyrannosaur arms are short when compared to other known predators. Horner argues that the arms were too short to make the necessary gripping force to hold on to prey.^[95]
Tyrannosaurs had large olfactory bulbs and olfactory nerves (relative to their brain size). These suggest a highly developed sense of smell which could sniff out carcasses over great distances, as modern vultures do. Research on the olfactory bulbs of dinosaurs has shown that Tyrannosaurus had the most highly developed sense of smell of 21 sampled dinosaurs.^[96] Opponents of the pure scavenger hypothesis have used the example of vultures in the opposite way, arguing that the scavenger hypothesis is implausible because the only modern pure scavengers are large gliding birds, which use their keen senses and energy-efficient gliding to cover vast areas economically.^[97] However, researchers from Glasgow concluded that an ecosystem as productive as the current Serengeti would provide sufficient carrion for a large theropod scavenger, although the theropod might have had to be cold-blooded in order to get more calories from carrion than it spent on foraging (see Warm-bloodedness of dinosaurs). They also suggested that modern ecosystems like Serengeti have no large terrestrial scavengers because gliding birds now do the job much more efficiently, while large theropods did not face competition for the scavenger ecological niche from gliding birds.^[98]
Tyrannosaur teeth could crush bone, and therefore could extract as much food (bone marrow) as possible from carcass remnants, usually the least nutritious parts. Karen Chin and colleagues have found bone fragments in coprolites (fossilized dung) that they attribute to tyrannosaurs, but point out that a tyrannosaur's teeth were not well adapted to systematically chewing bone like hyenas do to extract marrow.^[99]
Since at least some of Tyrannosaurus's potential prey could move quickly, evidence that it walked instead of ran could indicate that it was a scavenger.^[93]^[100] On the other hand, recent analyses suggest that Tyrannosaurus, while slower than large modern terrestrial predators, may well have been fast enough to prey on large hadrosaurs and ceratopsians.^[78]^[89]

The eye-sockets of Tyrannosaurus rex faced mainly forwards, giving it good binocular vision.

Other evidence suggests hunting behavior in Tyrannosaurus. The eye-sockets of tyrannosaurs are positioned so that the eyes would point forward, giving them binocular vision slightly better than that of modern hawks. He also pointed out that the tyrannosaur lineage had a history of steadily improving binocular vision. It is hard to see how natural selection would have favored this long-term trend if tyrannosaurs had been pure scavengers, which would not have needed the advanced depth perception that stereoscopic vision provides.^[14]^[15] In modern animals, binocular vision is found mainly in predators.

Restoration of a Tyrannosaurus (based on MOR 980) with parasite infections, which might be the cause of scars seen in the skulls of several specimens that were previously explained by intraspecific attacks

A skeleton of the hadrosaurid Edmontosaurus annectens has been described from Montana with healed tyrannosaur-inflicted damage on its tail vertebrae. The fact that the damage seems to have healed suggests that the Edmontosaurus survived a tyrannosaur's attack on a living target, i.e. the tyrannosaur had attempted active predation.^[101] There is also evidence for an aggressive interaction between a Triceratops and a Tyrannosaurus in the form of partially healed tyrannosaur tooth marks on a Triceratops brow horn and squamosal (a bone of the neck frill); the bitten horn is also broken, with new bone growth after the break. It is not known what the exact nature of the interaction was, though: either animal could have been the aggressor.^[102] When examining Sue, paleontologist Pete Larson found a broken and healed fibula and tail vertebrae, scarred facial bones and a tooth from another Tyrannosaurus embedded in a neck vertebra. If correct, these might be strong evidence for aggressive behavior between tyrannosaurs but whether it would have been competition for food and mates or active cannibalism is unclear.^[103] However, further recent investigation of these purported wounds has shown that most are infections rather than injuries (or simply damage to the fossil after death) and the few injuries are too general to be indicative of intraspecific conflict.^[93] A 2009 study showed that holes in the skulls of several specimens might have been caused by Trichomonas-like parasites that commonly infect avians.^[104]

Some researchers argue that if Tyrannosaurus were a scavenger, another dinosaur had to be the top predator in the Amerasian Upper Cretaceous. Top prey was the larger marginocephalians and ornithopods. The other tyrannosaurids share so many characteristics that only small dromaeosaurs remain as feasible top predators. In this light, scavenger hypothesis adherents have suggested that the size and power of tyrannosaurs allowed them to steal kills from smaller predators.^[100] Most paleontologists accept that Tyrannosaurus was both an active predator and a scavenger like all large carnivores.

History

Skeletal restoration by William D. Matthew from 1905, which was the first reconstruction of Tyrannosaurus rex ever published^[105]

Henry Fairfield Osborn, president of the American Museum of Natural History, named Tyrannosaurus rex in 1905. The generic name is derived from the Greek words τυραννος (tyrannos, meaning "tyrant") and σαυρος (sauros, meaning "lizard"). Osborn used the Latin word rex, meaning "king", for the specific name. The full binomial therefore translates to "tyrant lizard king," emphasizing the animal's size and perceived dominance over other species of the time.^[51]

Earliest finds

Teeth from what is now documented as a Tyrannosaurus rex were found in 1874 by A. Lakes near Golden, Colorado. In the early 1890s, J. B. Hatcher collected postcranial elements in eastern Wyoming. The fossils were believed to be from a large species of Ornithomimus (O. grandis) but are now considered Tyrannosaurus rex. Vertebral fragments found by E. D. Cope in western South Dakota in 1892 and named as Manospondylus gigas have also been reclassified as Tyrannosaurus rex.^[106]

Scale model of the never-completed Tyrannosaurus rex exhibit planned for the American Museum of Natural History by H.F. Osborn.

Barnum Brown, assistant curator of the American Museum of Natural History, found the first partial skeleton of Tyrannosaurus rex in eastern Wyoming in 1900. H. F. Osborn originally named this skeleton Dynamosaurus imperiosus in a paper in 1905. Brown found another partial skeleton in the Hell Creek Formation in Montana in 1902. Osborn used this holotype to describe Tyrannosaurus rex in the same paper in which D. imperiosus was described.^[107] Had it not been for page order, Dynamosaurus would have become the official name. The original Dynamosaurus material resides in the collections of the Natural History Museum, London.^[108]

In total, Brown found five Tyrannosaurus partial skeletons. In 1941, Brown's 1902 find was sold to the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania. Brown's fourth and largest find, also from Hell Creek, is on display in the American Museum of Natural History in New York.^[53]

Although there are numerous skeletons in the world, only one track has been documented — at Philmont Scout Ranch in northeast New Mexico. It was discovered in 1983 and identified and documented in 1994.^[109]

Notable specimens

Main article: Specimens of Tyrannosaurus

"Sue" the Tyrannosaurus, Field Museum of Natural History, Chicago

Sue Hendrickson, amateur paleontologist, discovered the most complete (approximately 85%) and, until 2001, the largest, Tyrannosaurus fossil skeleton known in the Hell Creek Formation near Faith, South Dakota, on 12 August 1990. This Tyrannosaurus, nicknamed "Sue" in her honor, was the object of a legal battle over its ownership. In 1997 this was settled in favor of Maurice Williams, the original land owner. The fossil collection was purchased by the Field Museum of Natural History at auction for USD 7.6 million, making it the most expensive dinosaur skeleton to date. From 1998 to 1999 Field Museum of Natural History preparators spent 30,000 hours taking the rock off each of the bones. The bones were then shipped off to New Jersey where the mount was made. The finished mount was then taken apart, and along with the bones, shipped back to Chicago for the final assembly. The mounted skeleton opened to the public on May 17, 2000 in the great hall (Stanley Field Hall) at the Field Museum of Natural History. A study of this specimen's fossilized bones showed that "Sue" reached full size at age 19 and died at age 28, the longest any tyrannosaur is known to have lived.^[110] Early speculation that Sue may have died from a bite to the back of the head was not confirmed. Though subsequent study showed many pathologies in the skeleton, no bite marks were found.^[111] Damage to the back of the skull may have been caused by post-mortem trampling. Recent speculation indicates that "Sue" may have died of starvation after contracting a parasitic infection from eating diseased meat; the resulting infection would have caused inflammation in the throat, ultimately leading "Sue" to starve because she could no longer swallow food. This hypothesis is substantiated by smooth-edged holes in her skull which are similar to those caused in modern-day birds that contract the same parasite.^[112]

Another Tyrannosaurus, nicknamed "Stan", in honor of amateur paleontologist Stan Sacrison, was found in the Hell Creek Formation near Buffalo, South Dakota, in the spring of 1987. After 30,000 hours of digging and preparing, a 65% complete skeleton emerged. Stan is currently on display in the Black Hills Museum of Natural History Exhibit in Hill City, South Dakota, after an extensive world tour. This tyrannosaur, too, was found to have many bone pathologies, including broken and healed ribs, a broken (and healed) neck and a spectacular hole in the back of its head, about the size of a Tyrannosaurus tooth. Both "Stan" and "Sue" were examined by Peter Larson.

In the summer of 2000, Jack Horner discovered five Tyrannosaurus skeletons near the Fort Peck Reservoir in Montana. One of the specimens, dubbed "C. rex," was reported to be perhaps the largest Tyrannosaurus ever found.^[113]

"Jane" at the Burpee Museum in Rockford, Illinois

In 2001, a 50% complete skeleton of a juvenile Tyrannosaurus was discovered in the Hell Creek Formation in Montana, by a crew from the Burpee Museum of Natural History of Rockford, Illinois. Dubbed "Jane the Rockford T-Rex," the find was initially considered the first known skeleton of the pygmy tyrannosaurid Nanotyrannus but subsequent research has revealed that it is more likely a juvenile Tyrannosaurus.^[114] It is the most complete and best preserved juvenile example known to date. Jane has been examined by Jack Horner, Pete Larson, Robert Bakker, Greg Erickson, and several other renowned paleontologists, because of the uniqueness of her age. "Jane" is currently on exhibit at the Burpee Museum of Natural History in Rockford, Illinois.^[115]^[116]

In a press release on 7 April 2006, Montana State University revealed that it possessed the largest Tyrannosaurus skull yet discovered. Discovered in the 1960s and only recently reconstructed, the skull measures 59 inches (150 cm) long compared to the 55.4 inches (141 cm) of "Sue's" skull, a difference of 6.5%.^[117]^[118]

Appearances in popular culture

Main article: Tyrannosaurus in popular culture

Since it was first described in 1905, Tyrannosaurus rex has become the most widely recognized dinosaur species in popular culture. It is the only dinosaur that is commonly known to the general public by its full scientific name (binomial name) (Tyrannosaurus rex), and the scientific abbreviation T. rex has also come into wide usage (commonly abbreviated "T-Rex").^[1] Robert T. Bakker notes this in The Dinosaur Heresies and explains that a name like "Tyrannosaurus rex is just irresistible to the tongue.

Tyrannosauridae

2009-11-22T06:30:00.000-08:00

Tyrannosauridae adalah salah satu suku dinosaurus karnivora. Nama "tyrann" berarti penguasa. Anggota dari genus ini memiliki ciri khas yaitu memiliki tulang pinggul yang kuat untuk menopang beban tubuhnya, sehingga dapat berdiri dengan dua kakinya. Selain itu, genus tyrannosauridae memiliki gigi yang tajam dan tulang rahang yang kuat. Anggota dari genus ini bervariasi mulai dari ignitochus sampai T-rex. Suku tyrannosauridae memiliki rekor kecepatan yang cukup tinggi, mencapai 70 km/jam (untuk T-rex).

Tyrannosauridae dulunya diklasifikasikan dalam bangsa carnosauria bersama dengan theropod, namun penelaahan filogenetik akhir-akhir ini menentukan bahwa tyrannosauridae berada dalam kelompok coelurosaur, sebuah kelompok yang juga termasuk ornithomimid dan maniraptora.

Tyrannosauridae memiliki keterkaitan yang lebih besar dengan dromaeosaurid daripada hewan pemangsa besar lain seperti allosarid.

Ciri-ciri tyrannosauridae adalah tengkorak yang lebar dan besar, leher yang pendek dan keras, serta lengan yang hanya mempunyai dua digit.

Berat: lebih dari 6,4 ton
Panjang: lebih dari 14 meter (lebih dari 46 kaki)
Lokasi/Tempat: Eropa Barat, Amerika Utara, Asia Tengah dan Timur (tergantung spesies)
Zaman: Cretaceous Akhir

[sunting] Daftar spesies

Tyrannosauridae terdiri dari beberapa genera dan spesies, di mana Tyrannosaurus rex adalah yang paling terkenal. Berikut adalah seluruh genera tyrannosauridae yang telah diketahui:

Superfamilia Tyrannosauroidea
- (tiranosaurus primitif)
- Familia TYRANNOSAURIDAE
  - Aublysodon
  - Deinodon
  - Subfamilia Albertosaurinae
    - Gorgosaurus
    - Albertosaurus
  - Subfamilia Tyrannosaurinae
    - Alioramus
    - Tyrannosaurini Suku
      - Daspletosaurus
      - Tarbosaurus
      - Nanotyrannus
      - Tyrannosaurus

Tips Membeli Mobil Bekas

2009-11-22T06:26:00.000-08:00

Apabila kondisi keuangan tidak memungkinkan untuk membeli mobil baru, maka membeli mobil bekas membantu anda untuk lebih leluasa mencari mobil yang paling sesuai dengan kebutuhan transportasi anda. Bahkan kebutuhan prestise. Anda juga bisa mendapatkan mobil berkualitas dengan harga terjangkau.

Hal yang perlu dipikirkan dalam proses membeli mobil bekas adalah menilai secara detail kebutuhan transportasi anda. Berikut beberapa pertimbangan yang bisa Anda terapkan :

1. Hitung seberapa besar kemampuan finansial untuk membeli mobil, termasuk uang muka dan pembayaran bulanan bila melalui kredit, yang paling aman adalah menentukan dulu berapa besar kemampuan keuangan untuk membayar angsuran bulanan. Cara yang gampang adalah tentukan angsuran tidak boleh lebih dari 20% penghasilan per bulan setelah dipotong pengeluaran. Perhitungkan juga biaya perawatan, pajak, asuransi dan biaya operasional.

Bayarlah uang muka setidaknya 10% dari harga mobil. Kurang dari itu, penyedia kredit akan meragukan kemampuan finansial anda. Jadi kalau anda punya uang cash, lebih baik pakai untuk uang muka. Langkah ini juga akan mengurangi beban utang pokok yang berkaitan dengan angsuran bulanan.

2. Tujuan membeli mobil

Tentukan jenis mobil yang akan dibeli berdasarkan penggunaannya. Misal bila digunakan untuk menjemput anak sekolah maka pilihlah mobil yang menawarkan ruang lega. Atau bila digunakan untuk keperluan transportasi kerja maka pilihlah yang nyaman dan irit bahan bakar. Gaya hidup anda juga berperan menentukan jenis mobil yang akan dibeli.

3. Tentukan fitur-fitur yang harus ada,

Tulis semua dalam list. termasuk pula fitur-fitur safety seperti rem ABS, airbag, child door lock, AC, aneka macam power, CD charger dan lain-lain.

4. Buka tutup mesin

Perhatikan apakah ada pipa yang bocor, belt yang aus, oli yang berceceran.

5. Analisa kelebihan dan kekurangannya merek mobil yang Anda inginkan

Anda bisa mendapatkan informasi dari teman yang pernah menggunakan mobil yang diincar. Cari informasi sebanyak-banyaknya dari masing-masing merek itu termasuk resale value, performa, layanan perbaikan dan harga/ketersediaan komponennya. Dari sana anda bisa menentukan mobil mana yang benar-benar sesuai.

6. Pastikan anda mengetahui sejarah mobil ini termasuk perawatannya.

Harus di ingat, membeli mobil bekas adalah membeli problem orang lain. Hal ini bisa diketahui dari salah satunya kartu perawatan mobil. Gali informasi sedetail mungkin termasuk apakah pernah tenggelam, kecelakaan, turun mesin dll. Sebelum memutuskan untuk membelinya, mintalah mekanik ahli untuk memeriksanya.

7. Test drive

Usahakan anda mendapat kesempatan melakukan test drive sejauh mungkin dengan aneka variasi jalan. Bisa juga mencoba ke daerah dimana mobil itu akan sering digunakan. Duduklah di kursi pengemudi, dan periksa apakah seluruh indikator bekerja baik, demikian pula lampu indikator. Periksa juga tanda-tanda kerusakan karena air.

Periksa sistem safety, mulai dari seat belt, head restrain, struktur atap, child seat anchor. Demikian pula jarak pandang dan daya pancar lampu utama. Hal itu bisa dilakukan saat test drive. Cobalah untuk mengendarai mobil pada kecepatan 60 - 80 km/jam dan rasakan apakah pergantian gigi bisa lembut, kemudi selalu lurus, ketika direm tetap stabil, dan ketika menikung juga smooth.

Hati-hati dengan pemalsuan odometer. Hal ini sering dilakukan penjual nakal yang ingin meningkatkan value mobil yang dijualnya. Jadi jangan tertipu dengan angka-angka yang tertera di odometer.

8. Pikiran harus tetap dingin.

Tinggalkan penjual bila harga yang ditawarkan terlalu tinggi, meskipun mobil impian anda sudah menunggu. Kemampuan negoisasi anda akan terasah dengan berjalannya waktu. Pastikan anda tahu harga pasaran mobil yang diincar, dan mulailah menawar dibawah harga itu. Lebih mudah menaikkan tawaran daripada menurunkannya.

Cara Merawat Mobil Yang Benar

2009-11-22T06:21:00.000-08:00

CARA PERAWATAN MOBIL YANG BENAR

Mobil disiram air bersih sampai rata, ingat jangan mencuci di bawah terik sinar matahatri langsung…
Campurkan air dengan sedikit shampoo, sampai menimbulkan busa di air tersebut, usapkan mobil dengan menggunakan sponge bersih rata, jangan ditekan atau memutar, sebaiknya satu arah.
bilas sisa shampoo tersebut dengan air bersih, sampai benar-benar bersih dan bebas dari shmpoo.
keringkan air pembilasan tersebut dengan Chamoice ( kanebo ) perlahan-lahan, jangan ditekan dan memutar, buat satu arah, caranya ; Chamoice ( kanebo ) dilipat 4 bagian dan jangan lupa untuk selalu membilas Chamoicetersebut dengan air bersih.
keringkan sisa kelembaban dengan kain katun bersih atau micro fiber karena Chamoice ( kanebo ) tidak dapat mengeringkan 100%.
Pada saat pengeringan terdapat beberapa kasus yang tidak dapat hilang pada bagian body dan kaca, seperti : jamur air, aspal jalanan, oksidasi jalan, lumpur, getah pohon dan lain-lain. anda dapat menggunakan produk poles dengan menggunakan bahan GLARE(Glassplexin/Non Wax) yang dapat menghasilkan kualitas kilau dan ketahanan kilau warna cat yang optimal untuk waktu yang lama

APA ITU GLARE….??????????

GLARE bukanlah silicon, wax, polymer, atau resin glaze, bahan dasarnya yang membuat GLARE berbeda dengan bahan yang lain. GLARE berbahan dasar Glassplexin yang dapat berubah menjadi kaca dan kaca merupakan satu-satunya bahan yang dikenal sebagai bahan yang dapat menyaring bahaya sinar ultra violet dari matahari..

Glare dapat melindungi kendaraan anda dari oksidasi, korosi dan cuaca buruk, glare juga melindungi kendaraan anda terhadap zat-zat yang berbahaya lain seperti : percikan garam jalanan, semburan garam, polusi udara, keasaman cuaca, dan zat alkalin dari pembersih. Glare menghasilkan meningkatkan kilau alami pada kendaraan anda. Glare juga menolak dari benda asing. membuat kendaraan anda mudah untuk dibersihkan karena menghilangkan kotoran-kotoran membandel seperti aspal, lumpur, getah pohon, kotoran burung, noda makanan ( termasuk telur ) tinta dan kelebihan semburan cat……

CARA PERAWATAN MOBIL PASCA PEMOLESAN DENGAN GLARE

Jika tidak terkena hujan, 2 hari jangan di cuci
Jika terkena hujan, siram dengan air bersih kemudian di lap dengan kanebo setelah itu dengan kain kaos/micro fiber

PENCUCIAN

Jika Hujan, lakukan pencucian setiap har, maksimum 2×24 jam harus di cuci, air hujan harus dibilas dahulu dengan air bersih

SHAMPOO

Shampoo harus PH balance, Non wax ( dianjurkan memakai shampoo Glare )

Shampoo digunakan apabila kondisi mobil kotor sekali ( dari luar kota, terkena kotoran burung, tanah liat ) Reguler/teratur 1x seminggu

PENGELAPAN

Melakukan pengelapan jangan ditekan ( hanya diusap saja )

Lap pertama dengan lap kanebo, lap kedua dengan kain kaos/micro fiber

Lap harus benar-benar dalam keadaan bersih

Dalam melakukan pengelapan harus mengambang dan tanpa tenaga

Cuci searah dan bersihkan bagian atasnya dahulu

Basahi dahulu mobil dengan air mengalir selama 2 menit, baru sponge dengan air

Jangan mencuci mobil di bawah terik matahari langsung

Debu : dibersihkan dengan kemoceng bulu domba

Bila malam hari hujan dan tidak sempat mencuci, kap mesin depan diangkat agar air mengalir dan tidak menimbulkan jamur pada Body mobil anda.

Setting Blog

2009-11-15T23:04:00.000-08:00

Sampai sejauh ini blog telah tersedia da sudah dapat diakses. Namun ada baiknya sebelum melakukan pengisisan blog dan mempublikasinya, kita lakukan beberapa setting-an berikut ini. Setting dilakukan dalam Panel Kontrol yang ada pada akun bolg kita. Untuk Masuk ke panel Kontrol terlebih dahulu harus masuk ke akun blog kita, klik Panel Kontrol (kanan atas halaman web).

stevenson

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