Coelophysis bauri

Coelophysis bauri was a small, slender theropod that lived in what is now the south-western United States late in the Triassic. A long narrow head, recurved serrated teeth, flexible neck, lightweight trunk, long hind limbs and an equally long balancing tail made it an agile bipedal predator. Its anatomy is exceptionally well known because the Whitaker Quarry at Ghost Ranch preserves hundreds of individuals, many articulated and representing several growth stages. Those skeletons are scientifically important, but their concentration does not by itself prove that Coelophysis hunted in coordinated packs or even lived in permanent groups.

Its fossils occur between approximately 212 and 205 million years ago. Values shown here are approximate and reflect the current curated seed dataset.

The skull was low and narrow, with a kink between the tooth-bearing premaxilla and maxilla and many small cutting teeth. The neck and tail were long, the vertebrae and limb bones were lightly constructed, and the hind limbs were proportionally elongated. Each hand carried three substantial clawed fingers and a much smaller fourth digit. The Ghost Ranch sample includes differently sized and differently proportioned skeletons, but proposed divisions into male and female body forms have not been demonstrated securely.

• Long, low skull with numerous recurved, serrated teeth
• Notch between the front and main tooth-bearing bones of the upper jaw
• Long, flexible neck and lightly constructed trunk
• Three strong clawed fingers plus a greatly reduced fourth digit
• Elongated hind limbs and narrow three-toed feet
• Very long tail that balanced the body over the hips
• Hollow or deeply excavated bones that inspired the genus name

David Baldwin collected the fragmentary original fossils in northern New Mexico in 1881. Edward Drinker Cope named them Coelurus bauri in 1887 and created the genus Coelophysis in 1889. The fossils were too incomplete to connect confidently with the spectacular skeletons discovered after crew member George Whitaker located the dense Ghost Ranch bonebed during Edwin H. Colbert’s 1947 American Museum expedition. After years of competing names, the International Commission on Zoological Nomenclature stabilized usage in 1996 by replacing the old lectotype with articulated Ghost Ranch skeleton AMNH FR 7224 as the neotype of C. bauri.

Discovery credit: David Baldwin, George Whitaker, Edwin H. Colbert.

Naming authors: Edward Drinker Cope.

Ghost Ranch lay within a broad low-latitude river system on western Pangaea. Seasonal channels crossed wooded floodplains under a strongly seasonal climate. Coelophysis shared this landscape with phytosaurs, aetosaurs, crocodylomorph relatives and many smaller reptiles rather than living in a dinosaur-dominated fauna.

Coelophysis probably caught small vertebrates and other manageable prey with its jaws and grasping hands. A 2006 re-examination showed that bones associated with the abdomen of the neotype belonged to a small crocodylomorph, not a juvenile Coelophysis, while the second supposed case did not preserve diagnostic gut contents. Cannibalism is therefore not supported by these famous specimens. The cause of the Ghost Ranch mass accumulation remains uncertain; flooding, drought mortality, transport and concentration in a channel may all have contributed.

• The Whitaker Quarry contains hundreds of animals ranging from small juveniles to adults.
• AMNH FR 7224 became the name-bearing neotype in 1996, more than a century after the species was named.
• A bronze cast in New York’s 81st Street subway helped prompt the re-examination of the supposed cannibal meal.
• Coelophysis became New Mexico’s official state fossil in 1981.

A research repository is not necessarily a public exhibit. Loan and display status can change, so check with the institution before visiting.

1. 01
   The Paleobiology Database

   Open source
2. 02
   Opinion 1842: Coelurus bauri Cope, 1887 (currently Coelophysis bauri): lectotype replaced by a neotype

   International Commission on Zoological Nomenclature · Bulletin of Zoological Nomenclature · 1996

   Open source
3. 03
   Prey choice and cannibalistic behaviour in the theropod Coelophysis

   Sterling J. Nesbitt, Alan H. Turner, Gregory M. Erickson, Mark A. Norell · Biology Letters · 2006

   Open source
4. 04
   Ghost Ranch: Fossil Site That Keeps Giving

   American Museum of Natural History

   Open source
5. 05
   Ghost Ranch, New Mexico: geologic tour and fossil history

   New Mexico Bureau of Geology & Mineral Resources

   Open source
6. 06
   Objecting to a Claim Dinosaur Was a Cannibal

   American Museum of Natural History · 2006

   Open source
7. 07
   Coelophysis Block: CMNH 10971

   Cleveland Museum of Natural History

   Open source