The myth of cannibalism in Coelophysis bauri

Argues that the small skeletons of Coelophysis preserved in the abdomens of large Coelophysis are not evidence of cannibalism, but instead the result of the skeletons overlapping after the animals died.

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It has been commonly accepted by both the general populace (due to popular books and documentaries) and the vertebrate paleontology community (through several technical publications) that the early theropod dinosaur Coelophysis engaged in cannibalism. This has been developed from two extraordinary specimens in which there appears to be a juvenile in the abdominal cavity of an adult. However, a careful review shows that the most likely explanation for the occurrence of juvenile remains within the body cavity of a larger animal is taphonomic, not behavioral.

Several lines of physical evidence indicate that cannibalism has not taken place. In certain places, both the left and right ribs of the adult overlay the juvenile remains, indicating that the smaller animal is actually underneath the adult. Also, volumetric analysis of the elements found within the chest cavity show that the bones would take up the maximum possible stomach size for this animal; not including any flesh that the bones would have on them. Furthermore, many elements of the putative cannibalized animal would be difficult to ingest, due to their size or shape. A partial ilium, a pes, and several articulated vertebrae are obvious examples of oddly shaped elements.

Therefore it is best viewed that the most parsimonious explanation for the apparent occurrence of a juvenile Coelophysis within the chest cavity of an adult Coelophysis is due to taphonomic features of the Ghost Ranch quarry, and is not reflective of the behavior of these animals.