New Mexico Geological Society Annual Spring Meeting — Abstracts

New Mexico Museum of Natural History’s Whitaker (Coelophysis) Quarry block (C-8-82) from the Apachean-aged Rock Point Formation of the Chinle Group contains abundant fossils of Coelophysis bauri, non-dinosaurian tetrapods, fish, and invertebrates. At least three specimens of C. bauri from the block have fossil fecal material directly associated with articulated skeletal material. These specimens apparently include material retained within posterior intestine (cololites) as well as evacuated material (coprolites). The cololits and coprolites occur between the ischia and the proximal caudal vertebrate, and postero-ventral to this area. Most of the coprolite material is formless and was apparently somewhat mixed with still-wet mud and silt at or near the time of death.

In P-77801, a small amount of coprolite material contains sparse bone fragments. The cololite and/or coprolite material associated with P-42352 is enigmatic; it consists of small bone fragments in a densely packed matrix of small (~1 mm long, by ~0.1 mm diameter), rod-shaped material. The coprolitic material associated with P-44552 is copious, formless, and rich in bone fragments. Bone fragments prepared from this material include a distal ulna, an ulnare, and partial phalanges that apparently pertain to juvenile Coelophysis and provide further evidence of cannibalism in this dinosaur. Additional material appears to include wrist bones, long-bone and rib fragments, and thin sheets similar to skull or pelvic bone.

Few examples of close associations between fecal material and vertebrate fossils are known, and this is a unique occurrence for a dinosaur. This unambiguous association can provide specific paleobiological information about Coelophysis including: diet (although modern scatological research indicates that many factors including temporal, ontogenetic and environmental factors affect generalizations about diet), digestion, metabolism (inferred from food lag time in the GI tract in turn inferred from the preservation of bone inclusions); size of the posterior intestinal tract, consistency and size of fecal pellets, position of cloaca, etc. The association of cololites or coprolites with skeletal material also has specific taphonomic implications for the mature of mortality, length of decay before burial and chemical conditions of burial.