"Dinosaurs like Coelophysis can survive on very little water. They are also light-boned, fast, and they are beautifully adapted for killing. Coelophysis may look like your average reptile, but it's not. It's unusually fast on it's feet, curious, and overt.

Coelophysis (see-low-FI-sis; "Hollow Form") is one of the earliest known genera of dinosaurs and a 3-meter long genus of coelophysoid theropod dinosaur which lived during the Norian stage of the late Triassic period in what is now North America. This dinosaur was one of the first dinosaurs to evolve. It is a very well-known early dinosaur as scientists have discovered hundreds of skeletons of this meat-eater. It was a relatively small, carnivorous theropod that lived during the Late Triassic - though for its time it was actually a fairly sizeable Theropod. Due to its sleek appearance and bone structure, its name means, 'Hollow Form'. It was about 2 metres long, and had a notably lightweight and yet lithe body.

Coelophysis is the oldest dinosaur known in North America, living around over 220 million years ago, during the Late Triassic Period. 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 dinosaur occasionally resorted to cannibalism.



As some of the very first dinosaurs ever to evolve, Coelophysis lived during the Late Triassic period, around 230-208 million years ago. It lived alongside other dinosaurs like Eoraptor, Plateosaurus, Liliensturnus, and Technosaurus.


Although small compared to other larger predatory dinosaurs, Coelophysis could get fairly large for an early dinosaur, growing just as big as a man, with adults ranging to a size of up to 4-5 feet tall, measuring 3 m (10 feet) long, and weighing less than 100 lbs. These size are generally divided into two specimen types - robust and gracile - and are thought to represent gender differentiation. Being a basal (one of the first) theropods, 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.

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 could survive on very little water and were also light-boned, fast, and beautifully adapted for killing.

But what made them unique were special hips and ankles that allowed them to stand perfectly balanced on two legs. With lightning fast reactions, they were built to survive. It was their speed and agility that gave them the edge in the Mid-Triassic


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.

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 a 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.