A caenagnathid tibia (Theropoda: Oviraptorosauria) from the upper Campanian Kirtland Formation of New Mexico

Abstract

Caenagnathid oviraptorosaurian dinosaurs, long considered enigmas, have now become relatively easy to recognize in the fossil record of Asia and North America. This has revealed their presence in several formations spanning the Late Cretaceous, providing new insights including showing that they were more widespread in the southern parts of North America than previously recognized. Here we add to this record by describing a nearly complete right tibia from the upper Campanian De-na-zin Member of the Kirtland Formation of New Mexico, which represents the first caenagnathid material from these beds. The bone is nearly identical in morphology and size to its counterpart in the Mongolian Elmisaurus rarus, reinforcing a suite of previously-identified features that allow for straightforward recognition of caenagnathid tibiae. The growing body of caenagnathid material continues to blur boundaries between features once considered distinct, raising doubts that some taxa established from sparse material, including Ojoraptorsaurus boerei, are actually valid.