A new caudipterid from the Lower Cretaceous of China with information on the evolution of the manus of Oviraptorosauria

Rui Qiu,Jialiang Zhang,Xiaolin Wang,Qiang Wang,Yiyun Ma,Ning Li

doi:10.1038/s41598-019-42547-6

Abstract

Caudipteridae is a basal clade of Oviraptorosauria, all known species from the Early Cretaceous Jehol Biota of northeastern China. They were one of the first feathered dinosaur groups discovered, and possessed avian-like pennaceous remiges and rectrices. Their discovery provided significant information on early oviraptorosaurian evolution and the origins of birds and feathers. Here we describe a new caudipterid species Xingtianosaurus ganqi gen. et sp. nov. from the Lower Cretaceous Yixian Formation of Liaoning Province, China. This new taxon differs from other caudipterids by a small pleurocoel close to the dorsal edge of the lateral surface of the dorsal vertebrate centrum, a humerus longer than the scapula, a proportionally long ulna, a relatively small radiale angle, and a relatively short metacarpal I. The phylogenetic results shows X. ganqi is an early diverging caudipterid. It exhibits a mosaic morphology, providing new morphological information on early manual evolution of Oviraptorosauria, and giving new light on the evolution of radiale angle among Coelurosauria.

Highlights

Oviraptorosauria is a group of unusual maniraptoran theropods from North America and East Asia[1]
This position is consistent with the primitive morphological features: the tail is proportionally short with fewer than 26 caudals; the humerus is relatively short, about half the length of the femur; metacarpal I is shorter than 50% length of the second; the proximal articular surface of manual phalanx I-1 is slightly concave; and the proximal portion of metatarsal III is compressed transversely
Caudipteryx can be distinguished from other oviraptorosaurs by its bizarre manual characters:[5,6] a strongly reduced manual digit III with only two short phalanges whose combined length is slightly longer than half the length of phalanx manual II-1; a large ligament pit on the manual phalanges; and an only shallowly concave proximal articular surface of manual phalanx I-1

Summary

Result

Humerus longer than the scapula, proportionally long ulna (as long as humerus), relatively small radiale angle (39°, compared to >48° in other oviraptorosaurs with known radiale angle), extremely short metacarpal I (

Discussion

Findings

Methods