Two New Specimens of Conchoraptor gracilis (Theropoda: Oviraptorosauria) from the Late Cretaceous of Mongolia

Despite a relatively abundant fossil record, the enigmatic and morphologically bizarre oviraptorosaurs suffer from a sparse and often taxonomically convoluted descriptive body of literature. Loss of important holotype material and continued reference to elusive papers often limits access for researchers interested in oviraptorosaur anatomy and systematics. In this work, we provide comprehensive, bone-by-bone descriptions of two extremely well-preserved specimens of Conchoraptor gracilis, an oviraptorid from the Late Cretaceous of Mongolia. This marks the most comprehensive anatomical description of this taxon - previous literature providing only short descriptions of fragmentary material or as a part of wider phylogenetic analyses. We present an updated diagnosis for the genus, including a novel cranial autapomorphy, that aims to increase the resolution by which small-bodied, crestless oviraptorids can be differentiated in the future. We particularly target the Conchoraptor/Heyuannia species complex, as these taxa tend to be conflated. A phylogenetic analysis of the described specimens, including character scoring for previously unknown regions of the skeleton, produces a topology consilient with the majority of recent oviraptorosaur phylogenies.