Since our most recent Factoid dealt with a new dinosaur, this week we’ll examine its closest relative in the park.
Built like a greyhound, this animal measured about 10 feet long and may have weighed 50-70 lbs.
Coelophysis is New Mexico’s state fossil.
Though well-known thanks to spectacular discoveries of over 1,000 individuals found at Ghost Ranch, New Mexico (the quarry that Larry’s block came from), it has experienced some taxonomic confusion. Since it was one of the few small meat-eating dinosaurs known for a long time, scientists tended to refer less well-preserved fossils to the genus, sometimes with less than good reasons. Similar dinosaurs from the southwest, like Camposaurus, Gojirasaurus, and Megapnosaurus tend to get lumped in with Coelophysis for one reason or another. Footprints called Grallator , found both in the southwest and Connecticut may have been made by Coelophysis or its close relative Podokesaurus (another animal that tends to get lumped in because of its poor preservation but similar build and time period.) Hopefully more and better discoveries will clear up our understanding of how Coelophysis relates to other members of its taxanomic family and, more importantly, how to tell them apart in the first place.
This animal seems to have established a very wide range for itself. Fossils and footprints indicate it lived at least as far west as Utah and Arizona (the west coast of Pangaea at the time), the aforementioned footprints in Connecticut may represent Coelophysis, and fossils regarded as a different species—C. rhodesiensis—have turned up in Zimbabwe and South Africa. Since Coelophysis lived before Pangaea broke into Gondwana to the south and Laurasia to the north, it makes sense, but that’s still several thousand miles.
An in-depth 2009 study concluded Coelophysis definitely has the features for fast running, but declined to provide a speed estimate. It did however note that the thigh bones of adults thickened as they grew. Unlike mammals, which tend to slow down as they grow older, these animals stayed as swift proportionately as they were when younger. With longer strides as adulst, that means they got slightly faster.
Like its cousin Dracoraptor, this species may have survived the Triassic extinction. However, Dracoraptor has more basic features than Coelophysis, which could mean they both had a common ancestor, rather than Dracoraptor giving rise to Coelophysis. Like in modern times, the Great Britain of the early Jurassic formed a cluster of islands, and Dracoraptor’s presence there may mean Britain was a sort of “Lost World” at that time—its life forms may have developed more slowly in isolation. More evidence would be needed to test this hypothesis.
Scientists have argued for decades over the possibility that Coelophysis cannibalized. Supposed babies found apparently inside a few adults have been shown to represent reptiles preserved underneath the skeletons in question. On the other hand, other evidence from coprolites associated with adult skeletons includes teeth from babies. As sensational as it may sound, it remains possible, if not confirmed, that Coelophysis ate its own young from time to time.