The taxonomy of a new parvicursorine alvarezsauroid specimen IVPP V20341 (Dinosauria: Theropoda) from the Upper Cretaceous Wulansuhai Formation of Bayan Mandahu, Inner Mongolia, China.

Michael Pittman,Xing Xu,Josef B Stiegler

doi:10.7717/peerj.986

Abstract

A new parvicursorine alvarezsauroid theropod specimen IVPP V20341 from the Upper Cretaceous Wulansuhai Formation of Bayan Mandahu, Inner Mongolia, China is described. IVPP V20341 appears to be distinguishable amongst alvarezsauroids by possible cervical procoely and relatively larger semi-circular caudal neural canals, but these features are not proposed as autapomorphies because current knowledge of alvarezsauroid necks and tails remains sparse. IVPP V20341 is distinguishable from Linhenykus—the sole parvicursorine at Bayan Mandahu—by the location of the origination points of the anterior caudal transverse processes; in IVPP V20341 this is the anterodorsal corner of the centra, whereas in Linhenykus it is the posterior end of the prezygapophyses. A number of additional tentative differences between IVPP V20341 and Linhenykus are also identified, but cannot be confirmed until further details of anatomical variation along the neck and tail are revealed by future finds. Thus, following the study of IVPP V20341 there are still seven parvicursorine species from the Upper Cretaceous Gobi Basin, but future finds could increase this to eight species.

Highlights

The Campanian-aged rocks of the Gobi basin of China and Mongolia have yielded alvarezsauroid theropods with impressive specialised body plans including the uniquely monodactyl parvicursorine Linhenykus monodactylus [1]
Only one parvicursorine - Linhenykus monodactylus Xu et al 2011 - is known from the same locality in Bayan Mandahu, Inner Mongolia, China as well as from the formation it belongs to, the Upper Cretaceous - possibly Campanian - Wulansuhai
107/6, [5]) and Shuvuuia (MPC 100/975, [23]) respectively may actual represent near complete series. These three neck specimens provide an indication of the basal alvarezsauroid and derived parvicursorine cervical conditions which should resemble that of IVPP V20341, so the absence of proceoly in all three is significant

Summary

Introduction

The Campanian-aged rocks of the Gobi basin of China and Mongolia have yielded alvarezsauroid theropods with impressive specialised body plans including the uniquely monodactyl parvicursorine Linhenykus monodactylus [1]. A potential pedal phalanx from digit IV is identified based on its seemingly short anteroposterior length, its apparently asymmetrical condyle in lateral view (like the suspected left pedal phalange III-2 described above) and a shaft with a steeply lowering ventral surface (Figure 5G). These features resemble those of the ?right pedal phalanx. IV-4 of Linhenykus (IVPP V17608 [20]), but the element in question is too poorly preserved for its position along the digit and its side of the body to be suggested

Discussion

Conclusions

Funding support