New information on the cranial morphology of Avimimus (Theropoda: Oviraptorosauria)

Abstract

ABSTRACTThe cranial morphology of the oviraptorosaurian Avimimus portentosus is described based on a new specimen, one that includes bones such as the nasal and the jugal, which had not been available or only incompletely preserved previously. The left and right nasals are fused together as in oviraptorids. Morphology of the jugal, which is not fused with the quadratojugal, and the postorbital indicate that the infratemporal fenestra is completely separate from the orbit, not confluent with the latter, as inferred previously. The left and right dentaries are fused together without a trace of suture. Such newly available information indicates that the skull of Avimimus is not as ‘avian’-like as inferred in previous studies. Rather, it shows a mixture of plesiomorphic and derived character states observed in Oviraptorosauria, consistent with an intermediate phylogenetic position of this dinosaur between Early Cretaceous basal oviraptorosaurians and the diverse clade of Caenagnathoidea.