A sauropod rib with an embedded theropod tooth: direct evidence for feeding behaviour in the Jehol group, China

A fragmentary rib from the Lower Cretaceous (Barremian) Yixian Formation in northeastern China preserves rare, direct evidence of feeding behaviour by an unidentified theropod. The rib, which comes from the holotype of Dongbetitan, preserves an embedded, broken theropod tooth. Comparison of the tooth with all known theropods from the Yixian Formation suggests that it belongs to a new taxon of medium-sized theropod. Given the large size difference between the sauropod and the theropod and the absence of reactive bone growth around the tooth, the bite likely occurred post-mortem during scavenging. Recognition of a new, medium-sized theropod increases the known diversity of taxa from the Yixian Formation and helps fill a gap in the theropod palaeoecology of that formation, which previously consisted of only small (<2 m) forms.