A new subadult specimen of oviraptorid Yulong mini (Theropoda: Oviraptorosauria) from the Upper Cretaceous Qiupa Formation of Luanchuan, central China

Abstract

Oviraptorosauria is a clade of maniraptoran dinosaurs that lived in the Cretaceous, with primitive toothed forms known from the Early Cretaceous, while the toothless forms lived towards the end of Cretaceous. Yulong mini is the first oviraptorid hatchling collected from the Upper Cretaceous Qiupa Formation of Luachuan, central China. Here, we describe a new non-hatchling individual of Yulong mini, which came from the same deposit of Luanchuan County. The new specimen includes three dorsal and 29 caudal vertebrae, partial pectoral girdles, and forelimbs. Phylogenetic analysis recovered the new specimen as a sister taxon of Yulong mini and is closely related to Nankangia from Ganzhou, which is located at the base of the oviraptorid phylogenetic tree. Osteohistological analysis suggests that it likely represents a subadult approximately five (or six) years old. Combining anatomical, phylogenetic, and osteohistological evidence, we assign the new specimen to Yulong mini, representing the first non-hatchling specimen of this taxon. We propose that the digit reduction in oviraptorosaurians was accompanied by a general forelimb reduction and an increased strength of the pectoral girdle. We also speculate that the variations in manus morphology could imply functional differences, which possibly relate to the ecologies of oviraptorosaurians.