Coelophysisis is one of the first known dinosaurs in the fossil record. It lived in southwestern North America about 215 to 200 million years ago in the late triassic period. It was first described and named in the late 19th century, by the famous paleontologist Edward Drinker Cope. Coelophysis means hollow form based on it's hollow bones. It had a slim body with a narrow pointed head, and a long S-shaped neck and sharp, serrated teeth. Small mammals and lizards would have been hunted by sight as Coelophysis had the large eyes of a hunter. It was about 7-9 feet long and 5-6 feet tall and probably weighed no more than 90-120 pounds. There were two variations a robust type and a slender type. Some paleontologists suggest this is an example of sexual dimorphism, while others claim they are different species. In 1947 paleontologist Edwin Colbert discovered more than 1,000 specimens of Coelophysis of varying ages and sizes at the Whitaker quarry of Ghost Ranch, New Mexico. This discovery indicates that Coelophysis traveld in huge family groups. Fossil evidence of cannibalism has found as well. There are adult Coelophysis' skeletons with remains of their own young inside the bellies. This suggests there must have been either a shortage of food, a population explosion or more likely, a combination of the two.
Ecology and behavior
Coelophysis was a typical small theropod probably preyed on the small, lizards and therapsids(mammals and mammal-like reptiles). It also may have ate a variety of fish and insects. It may also be possible since they roamed together in such large packs to take down large prey. There were a variety of large animals in Coelophysis environment. These included Placerias, a large herbivorous dicynodont, carnivourous Postosuchus, which was a rauisuchian reptile distantly related to crocodiles. There were other early dinosaurs as well including the prosauropod Plateosaurus and Eoraptor and early pterosaurs.