Describer

Zheng, Xu, You, Zhao and Dong 2009

Time

Cretaceous Early

Classification

Saurischia Theropoda Tetanurae Coelurosauria Dromaeosauridae

Diet

Carnivore

Fossilsite

Yixian Formation, Dawangzhangzi, Lingyuan, western Liaoning, China

Info

Abstract

Recent discoveries of basal dromaeosaurids from the Early Cretaceous Jiufotang and Yixian formations of Liaoning, China, add significant new information about the transition from non-avian dinosaurs to avians. Here we report on a new dromaeosaurid, Tianyuraptor ostromi gen. et sp. nov., from the Early Cretaceous Yixian Formation of western Liaoning, China, based on a nearly complete skeleton.

Tianyuraptor possesses several features only seen in other Liaoning dromaeosaurids, although to a less developed degree, and it also exhibits features unknown in Laurasian dromaeosaurids but present in the Gondwanan dromaeosaurids and basal avialans, thus reducing the morphological gap between these groups. Tianyuraptor possesses a comparatively small furcula and proportionally short forelimbs.

This lies in stark contrast to the possible capacity for flight in the microraptorines, which have proportionally long and robust forelimbs and large furculae. The presence of such striking differences between the Early Cretaceous Jehol dromaeosaurids reveals a great diversity in morphology, locomotion and ecology early in dromaeosaurid evolution.

Holotype

A nearly complete, articulated skeleton missing only the distal end of the tail, housed in Tianyu Museum of Nature (STM1–3).

Etymology

‘Tianyu’ is derived from the name of the museum that has the holotype, and ‘raptor’ refers to the Latin for ‘robber’. The specific name is in honour of John Ostrom, who contributed greatly to the study of dromaeosaurid fossils.

Diagnosis

A medium-sized dromaeosaurid that differs from other dromaeosaurids in the following derived features: length of the middle caudal vertebrae more than twice that of the dorsal vertebrae, a small and extremely slender furcula, and an elongated hindlimb about three times as long as the dorsal series.