Coelophysis

*Coelophysis bauri*

***Coelophysis*** (see - low - FI - sis) (Greek meaning "hollow form") was a dinosaur from the Late Triassic Period, living around 202 to 196 million years ago. It is the oldest dinosaur found in North America and scientists have discovered hundreds of skeletons of it.

*Coelophysis* could get fairly large for an early dinosaur, with adults ranging to a size of up to 3 meters (10 feet) and 1 meter (3 feet) tall. These sizes are generally divided into two specimen types - robust andmehpsaa.

It was a meat-eater, being a basal (one of the first) theropods, and it had some characteristics which were lost on later members of the theropod family. It still had four fingers, although the fourth digit was quite small.

The remains of hundreds of individuals were found at Ghost Ranch in New Mexico, which provided scientists with an unprecedented opportunity to study the individual differences within a large herd of the same dinosaurs.

Like other early carnivores, *Coelophysis* had many small, sharp teeth. As is shown by the vast numbers of individuals at Ghost Ranch, it is evident that early dinosaurs exhibited social behavior to the extent of congregating in large herds. The exact purpose of this large gathering is not known, but some scientists feel that it may have been breeding season.

*Coelophysis* is at the base of the family tree of a great many dinosaurs including all the dilophosaurs, oviraptors, ornithomimids and the ever popular "Raptor" family which includes *Velociraptor*, *Utahraptor*, and *Deinonychus*.

Note that the original type material, which may or may not belong to the same kind of animal as those later found at Ghost Ranch, has been given its own (disputed) genus: *Eucoelophysis* ("true *Coelophysis*").

A *Coelophysis* skull became the first dinosaur fossil to be taken into space in January 1998 when the Space Shuttle "Endeavor" carried a specimen from the Carnegie Museum to the Mir Space Station.

It wasn't until in 2002 that the remains from the Ghost Ranch specimens have been re-examined, and later concluded that the "juvenile coelophysids" found in the abdominal cavities were actually from small crurotarsan reptiles such as *Hesperosuchus*. This is likely the result of the fossil of a larger individual overlapping a smaller one. With this discovery and to date, *Coelophysis* would no longer be recognized for having a cannibalistic behavior.

Predators such as *Ceolophysis* had S-shaped necks that they could straighten in an instant to snap up small prey. It also had a flexible neck too.

## Name & Discovery

It was Named in 1887, the type species of Coelophysis was originally named as a species of Coelurus. Edward Drinker Cope first named Coelophysis in 1889 to name a new genus, outside of Coelurus and Tanystrophaeus to which C. bauri was previously classified in for C. bauri, C. willistoni and C. longicollis.

## Sexual Dimorphism

There were thought to be 2 species but it was found that males were bigger than females.

## Description

Coelophysis is known from a number of complete fossil skeletons of the species C. bauri, which was a lightly built dinosaur which measured up to 3 metres (9.8 feet) in length and which was more than a meter tall at the hips. Paul (1988) estimated the weight of the gracile form at 15 kg (33 lbs), and the weight of the robust form at 20 kilograms (44 lbs). Coelophysis was a bipedal, carnivorous, theropod dinosaur that was a fast and agile runner.

Recent studies on activity levels and the genus occurring in climates that could get colder than previously thought have changed opinions on the animal's integument. This revived an old hypothesis from the 1980s that *Coelophysis* was covered in feathers. The study indicated only a feathered animal of *Coelophysis* shape and size could have survived the cold so handily. Many paleontologists has thus begun returning the 1980s reconstructions for an idea of how the animal looked in life.

## Classification

Coelophysis is a distinct taxonomic unit (genus), composed of two species; C. bauri and C. rhodesiensis (the latter formerly classified as the genus Megapnosaurus). 2 additional originally described species, C. longicollis and C. willistoni, are now considered synonymous with C. bauri. C. rhodesiensis is probably part of this generic complex, and is known from the Jurassic of southern Africa.

## JPInstitute.com Description

Coelophysis is a very well known early dinosaur as scientists have discovered hundreds of skeletons of this meat-eater. It is the oldest dinosaur known in North America. It was a swift hunter that seemed to eat almost anything it could catch - including other Coelophysis! Some of the skeletons found in New Mexico had the remains of other Coelophysis in their stomachs, making it a cannibalistic dinosaur.

Coelophysis could get fairly large for an early dinosaur, with adults ranging in size from 5 to 10 feet. These sizes are generally divided into two specimen types - robust and graceful- and are thought to represent gender differentiation. Being a basal (one of the first) therapod, it had some characteristics that were lost on later members of the therapod family. It still had four fingers, although the fourth digit was quite small.

The remains of hundreds of individuals were found at Ghost Ranch in New Mexico, which provided scientists with an unprecedented opportunity to study the individual differences within a large herd of the same dinosaurs.

Like other early carnivores, Coelophysis had many small, sharp teeth. As is shown by the vast numbers of individuals at Ghost Ranch, it is evident that early dinosaurs exhibited social behavior to the extent of congregating in large herds. The exact purpose of this large gathering is not known, but some scientists feel that it may have been breeding season.

Coelophysis is at the base of the family tree of a great many dinosaurs including all the dilophosaurs, oviraptors, ornithomimids and the ever-popular "raptor" family, which includes Velociraptor, Utahraptor, and Deinonychus.

Note that the original type material, which may or may not belong to the same kind of animal as those later found at Ghost Ranch, has been given its own (disputed) genus: Eucoelophysis ("true Coelophysis").

A Coelophysis skull became the first dinosaur fossil to be taken into space in January, 1998 when the Space Shuttle "Endeavor" carried a specimen from the Carnegie Museum to the Mir Space Station.

## Dinosaur Field Guide Description

Coelophysis ("hollow form"') was one of the first meat-eating dinosaurs. When Coelophysis lived, dinosaurs had just evolved, and they did not yet dominate the land. Instead, giant relatives of crocodilians were the top predators, and armored crocodile relatives and ox-sized protomammals-primitive synapsids related to the ancestors of mammals were the big plant-eaters. Coelophysis was a minor predator in its environment, but it was very successful. Unlike their crocodilian relatives, Coelophysis and other early dinosaurs were fast-running, agile hunters. In 1947, hundreds of Coelophysis skeletons were found buried together at Ghost Ranch, New Mexico. This spectacular discovery included old individuals, babies, and all ages in between. Except for a few other reptiles, the only skeletons in this quarry were from Coelophysis. This suggests that these early dinosaurs would group together, at least occasionally. Some paleontologists think that this mass death might have happened when a pack of Coelophysis gathered near a watering hole and were buried by a flash flood. In the bellies of some of the Coelophysis were the skeletons of baby Coelophysis- it seems that they were eaten by the adults!

### Fun Facts

Coelophysis is known from more skeletons than any other meat-eating dinosaur of the Mesozoic.

### Trivia

Coelophysis is the state fossil of New Mexico.

## Links

http://web.archive.org/web/20040214155928fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_coelo.html#