CRYOLOPHOSAURUS

'''Cryolophosaurus''' (// or //, meaning "cold crest lizard") was a large bipedal dinosaur, with a bizarre crest on its head that looked like a Spanish comb. Due to the resemblance of this feature to Elvis Presley's pompadour haircut from the 1950s, this dinosaur was at one point informally known as "Elvisaurus".
''Cryolophosaurus'' was discovered in Antarctica's Early Jurassic Hanson Formation (former the upper Falla Formation) by paleontologist Dr. William Hammer in 1991. It is the first carnivorous dinosaur to be discovered in Antarctica and the first dinosaur of any kind from the continent to be officially named. Dating from the Early Jurassic Period, it is also the earliest tetanuran theropod yet discovered.

Contents

Description

Forests of the night

Classification

Discovery

References

External links

Description

''Cryolophosaurus'' was about 6 to 8 meters (20 to 26 feet) long, which is significantly smaller than the largest ''Allosaurus'', which reached up to 12 meters (40 feet) in length.
A high, narrow skull was discovered, 65 centimeters (25 inches) long. The peculiar nasal crest runs just over the eyes, where it rises up, perpendicular to the skull and fans out. It is furrowed, giving it a comb-like appearance. It is an extension of the skull bones, near the tear ducts, fused on either side to horns which rise from the eye sockets (orbital horns). While other theropods like the ''Monolophosaurus'' have crests, they usually run along the skull instead of across it.
The crest is too fragile to be used in combat, so it was probably used in mating displays.

Forests of the night

The remains of the ''Cryolophosaurus'' were found in the Hanson Formation with the remains of a very large prosauropod (related to plateosaurids like the ''Plateosaurus'' and ''Lufengosaurus''), a small pterosaur, a mammal-like reptile (a tritylodont, which is a type of synapsid about the size of a rat), and another unknown theropod. There were also fossilized tree trunks two meters away. The site is about 4,000 meters (13,000 feet) above sea level. During the early Jurassic it was a river bed on the southern coast of the supercontinent of Gondwana.
This supports the idea that, even at high altitudes, early Jurassic Antarctica had forests populated by a diverse range of species, at least along the coast. Even though Antarctica was closer to the equator and the world was considerably warmer than today, the climate was still cool temperate. Recent models of Jurassic air flow indicate that coastal areas probably never dropped much below freezing, although more extreme conditions existed inland. This suggests that dinosaurs could endure relatively cool environments and even possibly survive snow.
''Cryolophosaurus'' was found about 650 kilometers (400 miles) from the South Pole but, at the time it lived, this was about 1000km or so farther north. Cryolophosaurus, therefore, did not have to contend with the polar night.
The specimen was found in conjunction with a platter from the prosauropod which has led to speculation that it may have choked to death, although there is no concrete evidence of this one way or the other.

Classification

:"''Cryolophosaurus'' is also of significance because it represents the oldest known tetanuran from any continent — it is the only one from the Early Jurassic."
::—William R. Hammer
Classification is difficult because the ''Cryolophosaurus'' has a mix of primitive and advanced characteristics. The leg bone (femur) has traits of early theropods, while the skull resembles much later species, like China's ''Sinraptor'' and ''Yangchuanosaurus''. Originally, it was suspected that ''Cryolophosaurus'' might be a ceratosaur or even an early abelisaur, with some traits convergent with those of more advanced tetanurans. Mortimer ([1]) added ''Cryolophosaurus'' to the data from a study by Rauhut (2000) and found it to be even more primitive - a coelophysoid closely related to ''Dilophosaurus''. This animal gives fuel to the argument that tetanuran ''Carnosaurs'', like the Allosaurs, share a common ancestor and are closer than previously believed to the more "primitive" Ceratosaurus and its kin and that ''Cryolophosaurus'' could be the ancestor or close to the ancestor of both groups, accounting for the mixture of advanced and primitive characteristics. However, it is still believed by most researchers to be an early and primitive tetanuran. The most recent study that included ''Cryolophosaurus'', Smith ''et al.'' (2005), recovered this position.

Discovery

''Cryolophosaurus'' was originally collected during the 1990-91 austral summer, by William R. Hammer and his team, on Mount Kirkpatrick, in the Beardmore Glacier region of the Transantarctic Mountains. They were located in the siliceous siltstone of the Hanson Formation (formerly the upper Falla Formation) and dated to the Pliensbachian age of the early Jurassic.
In the summer of 1991, William R. Hammer, and an Ohio geologist, David Elliot, worked different outcrops in the Transantarctic Mountains near Beardmore Glacier. Each pursued separate goals but shared logistic expenses. Work in Antarctica is so expensive that scientific projects organize schedules to pool resources. At 13,000 feet (4,000 m) and 400 miles (640 km) from the South Pole, Elliot finds bones eroded out of a small outcrop. Fossils! He radios Hammer, who races over.
Hammer's team spent the next three weeks of the field season (January 1991) excavating 5,000 pounds (2300 kg) of the fossil-bearing rock with a gasoline-powered jackhammer. They recovered over 100 fossil bones, including those of the large meat-eating dinosaur, ''Cryolophosaurus ellioti.'' Hammer named the previously unknown dinosaur species after Elliot. ^[1]
It was formally named and described in 1994 by William R. Hammer and William J. Hickerson, in the journal ''Science''. The name ''Cryolophosaurus'' was dervived from the Greek κρυος (meaning 'cold' or 'frozen'), λοφος (meaning 'crest') and σαυρος (meaning 'lizard'). The name refers not the extreme conditions faced by the excavation team but to the relatively cool climate that the dinosaur lived in.
The remains include part of a skull (cranium), a jaw bone (mandible), parts of the backbone (30 vertebrae), hip bones (the ilium, ischium, and pubis), leg bones (femur and fibula), an ankle bone (tibiotarsus) and foot bones (metatarsals). The skull was partially crushed by the Beardmore Glacier, but the crushed front portion of the skull has been reconstructed.
During the 2003 season a field team returned and collected more material from the original site. In addition a second locality was discovered about 30 meters higher in the section on Mt. Kirkpatrick.
Hammer is a professor of geology and paleontology at Augustana College in Rock Island, Illinois and a curator at the Fryxell Geology Museum.

References

★ Hammer, W.R., and W. J. Hickerson (1994). "A crested theropod dinosaur from Antarctica." ''Science'', '264'(5160): 828-830. May 6, 1994. (abstract)

★ Smith, Hammer, and Currie (2005). "Osteology and phylogenetic relationships of ''Cryolophosaurus ellioti'' (Dinosauria: Theropoda): Implications for basal theropod evolution." ''Journal of Vertebrate Paleontology'', '25'(3): 116A-117A.

External links

★ Transantarctic Vertebrate Paleontology Project, official website for the NSF project conducting research on Cryolophosaurus and related fauna (photos, research information, publication list, geology, project members...)

★ Fryxell Geology Museum (photos, information)