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Abstract
Crocodilians employ unique feeding behaviors as compared to other predators in modern ecosystems. The use of inertial and rotational forces, coupled with immense jaw strength, allow crocodilians to consume large fauna with relative ease. Given the unique forces applied to crocodile modified carcasses, we would expect to find diagnostic traces of such feeding behavior on the skeletal remains of their prey that were not ingested. The goal of this research is to establish criteria for identifying crocodile feeding traces in the fossil record. Guided by a taphonomic and ichnologic framework, I interpret the feeding traces recorded on bones modified by Nile crocodiles (Crocodylus niloticus) in controlled feeding experiments. Building upon previous bone surface modification descriptions, I define crocodile feeding traces as ichnotaxa. I describe a new ichnogenus, Sicarichnus, which corresponds to a penetrative force that slips and incises the surrounding bone. I describe a new ichnospecies, Brutalichnus percussus, corresponding to marginal bone cracking. Using these ichnotaxa, I then describe patterns of bone surface modification that appear to be unique to Crocodylia and which reflect various observed feeding behaviors. I observe pairs of mechanically equivalent traces at distances equivalent to crocodile tooth spacing. Elongate, multi-directional traces correspond to the unique, rotational carcass disarticulation techniques used by crocodiles. Pairs of nearly identical traces, parallel and in close proximity to each other, are correlated to non-masticatory feeding. With compounding paleontological evidence, these traces could be a robust indicator of crocodile ecology in the fossil record. Fossils recovered from wetland depositional environments which demonstrate these traces have a high likelihood of having been lost or abandoned by crocodiles during feeding.
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