Alvarezsaurid osteology: new data on cranial anatomy

ABSTRACT

Alvarezsaurs were a group of theropod dinosaurs found in Asia, North America, South America and Europe during Jurassic and Cretaceous periods. In spite of being known by several specimens, diverse aspects of their anatomy remain poorly known. The aim of the present paper is to describe and analyse some points of the neuroanatomy of a newly collected alvarezsaurid specimen. A partial skeleton of an indeterminate Late Cretaceous alvarezsaurid theropod (HGM L08-59) from the collection of Henan Geological Museum in Zhengzhou, China, preserved a partial skull that allows to study some aspects of braincase anatomy. Anatomical features observed in HGM L08-59 and other alvarezsaurs indicate that members of this clade exhibited a notably enhanced somatosensory control during locomotion. The study of skull material of HGM L08-59 as well as that of other alvarezsaur skulls, sheds some doubts on the phylogenetic position of supposed Jurassic alvarezsaurs from China (i.e., Haplocheirus, Aorun and Shishugounykus). Further, some skull features of Haplocheirus are reminiscent to those of ornithomimosaurs and are dissimilar to alvarezsaurs. A comprehensive phylogenetic analysis will shed light on this complex topic that is highly relevant on discussions about early radiation of coelurosaurian theropods.

KEYWORDS:

• Alvarezsauridae
• Cretaceous
• neurocraniology
• phylogeny

Acknowledgments

This research was supported by PICT 2018-01390 awarded to FLA, and by the Slovak Research and Development Agency (APVV-18-0251) and the Scientific Grant Agency VEGA of the Ministry of Education, Science, Research and Sport of the Slovak Republic (grant #1/0853/17) awarded to MK. Special thanks to M. D. Ezcurra and F. E. Novas for shared information about the Haplocheirus holotype specimen. Our special thanks to Deb and Randy Lyons for their rigorous edit of the final version of the manuscript. Finally, we thank to two anonymous reviewers and the Editor-in-Chief G. Dyke for their comments that greatly improved the quality of our manuscript.

Disclosure of potential conflicts of interest

No potential conflict of interest was reported by the author(s).