Named By: Edward Drinker Cope - 1889.
Classification: Chordata, Reptilia, Dinosauria, Saurischia, Theropoda, Coelophysidae, Coelophysinae
Species: C. bauri.
Size: 2.8-3 meters long.
Known locations: USA, New Mexico and Arizona. Quite possibly other areas of the US and even further afield.
Time period: Carnian to Norian of the Triassic.
Fossil representation: Many specimens are known, in fact they are so numerous the exact figure is not easy to establish.
is frequently used as an example of the early dinosaurs. Its bipedal
stance from two legs that supported its body from underneath as opposed
to sticking out to the sides, smaller arms and head mounted on an
'S curved' neck give it the distinctive theropod look. Coelophysis
also had sharp recurved teeth that were serrated on the front and back
edges, making them perfect for slicing.
Inside, the limb bones were hollow making Coelophysis very light. This combined with the long legs mean that Coelophysis would have been able to easily cover a greater distance in the search for prey, suggesting that Coelophysis most probably lived the life of an opportunistic carnivore in that not only did it hunt for small animals, it may have actively sought out carrion as well.
It was long assumed that Coelophysis was cannibalistic. This view was based upon the remains of smaller creatures found in what would have been the gut of Coelophysis. Although upon first glance they appeared to be Coelophysis juveniles, later study in 2002 by Rob Gay proved that they were the bones of reptiles that belonged to the crurotarsan group. These reptiles were common during this time of the Triassic, and the evidence now points to the crurotarsan reptiles forming a key part of the diet of Coelophysis, at least in this fossil location.
Coelophysis remains can be sub divided into robust and gracile forms, and it is now thought that these represent males and females of the species. This sexual dimorphism is also clearly seen in group concentrations of Coelophysis remains, and shows that they would at times cluster together. It is still unknown if this is evidence of an established pack, or just a number of individuals taking advantage of an abundant food source like can be seen with bears fishing for salmon in rivers today.
The most famous group concentration of Coelophysis comes from the Ghost Ranch deposit discovered in 1947. It is thought by many that the Coelophysis individuals deposited there were killed by a flash flood, something that is considered to have been a frequent occurrence during this time. The specimens recovered from this deposit were in a much better state of preservation than the early fossils that had been described by Cope in 1889, and because of this, the phylogenetic position of Coelophysis would need to be shuffled around.
The original type specimen was in a very poor state of preservation, so poor in fact, some were uncertain about the legitimacy of assigning the Ghost Ranch specimens to the name Coelophysis. In 1991 the new name of Rioarribasaurus was assigned to these specimens but quickly contested on the grounds that the majority of the knowledge, written material and reconstruction of Coelophysis was based upon the Ghost Ranch fossils. Considering the arguments of the petition the ICZN voted to restore the name Coelophysis, and also decreed that a new type specimen of Coelophysis be taken from the Ghost Ranch deposits so that new specimens may be referred against more complete material. A consequence of this decision was Rioarribasaurus becoming a nomen rejectum (meaning 'rejected name'), and has since been placed as a synonym to Coelophysis.
Further to the above, some palaeontologists also think that a later dinosaur named Megapnosaurus is actually a late surviving Coelophysis. Support for this comes from striking similarities between the two dinosaurs. If it can be proven that Megapnosaurus is a synonym, the temporal range of Coelophysis would extend beyond the Norian and well into the early Jurassic.