Geologic Landscapes and Observations of Surrounding Nature: New Mexico’s state fossil

The state of New Mexico has recognized a state fossil and a state gem. The state gem will be presented in a later column.

The state fossil is Coelophysis (see-low-FYS-iss), an early Triassic dinosaur which first appeared in the Mid Triassic Period around 228 million years ago.

The genus name, Coelophysis, means “hollow form” and refers to the hollow limb bones. It was a small dinosaur compared with those that have appeared in movies. Coelophysis was almost 9 feet in length and about 3 feet high at the hips, with a long tail which probably acted as a counterweight when it was running on its two rear legs and maneuvering at high speeds.

The forelimbs ended in grasping hands with three functional, clawed fingers used for catching and holding prey It was thought to have weighed around 50 pounds and some researchers have speculated that it was warm-blooded. Coelophysis was probably an opportunistic feeder, eating both live prey and scavenging on dead materials.

The first remains of the fossil were found in 1881 and were classified by Edward D. Cope in 1889. In 1947, a large “graveyard” of Coelophysis was found at the Ghost Ranch in Rio Arriba County not far from the original find.

It is thought that the mass burial was caused by a flash flood which trapped other species in addition to this one. The great number of animals buried together near the Ghost Ranch suggests that the animals sometimes congregated in large “flocks.”

The Late Triassic Earth was still assembled into the supercontinent Pangaea, allowing animals to essentially walk between all the major continents, unimpeded by ocean barriers.

For more details, read “New Mexico Earth Matters,” Summer 2017 publication from New Mexico Tech.