A near-complete caudipterid pes from the Early Cretaceous Jehol Biota reveals insights into pedal anatomy and osteohistology of early oviraptorosaurs

The evolution of the pedal morphology and the ontogeny of early oviraptorosaur theropods remain inadequately understood, largely owing to the poor preservation of available material and the limitations of traditional observation methods. Here, we describe a particularly well-preserved and nearly complete pedal specimen (PMOL-AD00126) from the Lower Cretaceous Jehol Group of western Liaoning, P.R. China and assign it to Caudipteridae, an early-diverging clade of oviraptorosaurs. Three-dimensional reconstruction of the pes reveals numerous previously undocumented morphological features, including a subarctometatarsalian metatarsus, metatarsal I with pronounced dorsal and plantar prominences, distinct plantar ridges on metatarsals II and III, an elongated extensor ligament pit on metatarsal III and well-developed extensor ligament pits and articular ridges on the pedal phalanges. Histological analysis indicates that this individual had not attained complete somatic maturity. These newly-recognised morphological and histological characters provide significant insights not only into the taxonomy and ontogeny of Caudipteridae, but also into the evolution of early oviraptorosaurs.