A New Oviraptorid Dinosaur (Dinosauria: Oviraptorosauria) from the Late Cretaceous of Southern China and Its Paleobiogeographical Implications

Abstract

The Ganzhou area of Jiangxi Province, southern China is becoming one of the most productive oviraptorosaurian localities in the world. A new oviraptorid dinosaur was unearthed from the uppermost Upper Cretaceous Nanxiong Formation of Ganzhou area. It is characterized by an anterodorsally sloping occiput and quadrate (a feature shared with Citipati), a circular supratemporal fenestra that is much smaller than the lower temporal fenestra, and a dentary in which the dorsal margin above the external mandibular fenestra is strongly concave ventrally. The position of the anteroventral corner of the external naris in relation to the posterodorsal corner of the antorbital fenestra provides new insight into the craniofacial evolution of oviraptorosaurid dinosaurs. A phylogenetic analysis recovers the new taxon as closely related to the Mongolian Citipati. Six oviraptorid dinosaurs from the Nanxiong Formation (Ganzhou and Nanxiong) are distributed within three clades of the family. Each of the three clades from the Nanxiong Formation has close relatives in Inner Mongolia and Mongolia, and in both places each clade may have had a specific diet or occupied a different ecological niche. Oviraptorid dinosaurs were geographically widespread across Asia in the latest Cretaceous and were an important component of terrestrial ecosystems during this time.

A Late Cretaceous diversification of Asian oviraptorid dinosaurs: evidence from a new species preserved in an unusual posture

“…Tongtianlong differs from Huanansaurus 29 in skull morphology and forelimb proportions. There is a crest in Huanansaurus but not in Tongtianlong .…”

“…Complex pneumaticity in this region is common in oviraptorosaurs643). However, the pneumatic openings in Tongtianlong are much larger and more elaborate than the corresponding pneumaticity in the two Ganzhou oviraptorids with well-preserved cranial material, Huanansaurus 29 and Banji 26.…”

“…The anterior margin of the premaxilla is highly convex, which is an autapomorphy of Tongtianlong . Most other oviraptorosaurs have a straight anterior premaxilla (e.g., Citipati 42, Khaan 42), and this is also the case in the Ganzhou oviraptorid Huanasaurus 29. Yulong and the Ganzhou oviraptorid Banji have a slightly rounded anterior margin of the premaxilla in lateral view, but it is not nearly as convex as in Tongtianlong .…”

“…The divergence of the two branches defines the shape of the external naris. Anteroventral to the naris, a deeply concave fossa extends on the lateral surface of the premaxilla, as in Huanasaurus 29, Yulong 10, and Nemegtomaia 3738, but unlike the slightly concave surface in Citipati 6. The maxilla is very small and exposed only as a tiny sliver of bone in lateral view.…”

“…In total, more than 35 oviraptorosaur genera are now known. Many of the recent discoveries have come from China, particularly from three areas of the country: northern China (including Inner Mongolia and western Liaoning Province81214151617181920), central China (Henan Province2110), and southern China (including Guangdong and Jiangxi provinces9222324252627282930). The southern Chinese oviraptorosaurs are especially diverse.…”