A new sauropodiform dinosaur with a \u2018sauropodan\u2019 skull from the Lower Jurassic Lufeng Formation of Yunnan Province, China

Qian-Nan Zhang,Tao Wang,Hai-Lu You,Sankar Chatterjee

doi:10.1038/s41598-018-31874-9

Abstract

The Early Jurassic Lufeng Formation of Yunnan Province in southwestern China is one of the best fossil localities in the world for understanding the early radiation of sauropodomorph dinosaurs. It has yielded a rich assemblage of complete and three-dimensionally preserved skeletons of herbivorous dinosaurs that provide crucial morphological information for systematic and evolutionary studies. Here we describe a new taxon, Yizhousaurus sunae gen. et sp. nov., represented by a nearly complete skeleton with an exquisitely preserved skull and mandible. Yizhousaurus is distinguished from other non-sauropodan sauropodomorphs by a unique combination of plesiomorphic and apomorphic features, which increases our understanding of the anatomical variation on the relatively conservative ‘prosauropod’ cranial plan. Phylogenetic analysis resolves Yizhousaurus as a sauropodiform, showcasing a mosaic character suite combining plesiomorphic states in the postcranial skeleton with some more ‘sauropodan’-like features in the skull. Furthermore, Yizhousaurus is placed closer to the base of Sauropoda than other non-sauropodan sauropodomorphs currently known from the Lufeng Formation, adding another taxon to enrich the Lower Jurassic Lufeng dinosaur fauna.

Highlights

The Lufeng Jurassic strata is a typical continental redbed sequence that is traditionally divided into ‘Lower’ and ‘Upper’ Lufeng formations on the basis of lithology and fauna[7,8,9,10]
The strict consensus tree obtained from our phylogenetic analysis is relatively well-resolved (Fig. 7A), with Yizhousaurus recovered as a sauropodiform close to Anchisaurus and Mussaurus
It is obvious that large parts of sauropodomorph phylogeny have been reconstructed in the absence of well-preserved cranial material, an issue that is especially true for non-sauropodan sauropodiforms

Summary

Introduction

The Lufeng Jurassic strata is a typical continental redbed sequence that is traditionally divided into ‘Lower’ and ‘Upper’ Lufeng formations on the basis of lithology and fauna[7,8,9,10]. Sun et al.[9] recognized two distinctive vertebrate faunas corresponding to these two members in the Lufeng Basin, respectively Both faunas are dominated by abundant non-sauropodan sauropodomorph dinosaurs, but many of these Lufeng taxa are poorly known in detail or vaguely diagnosed; their validity and/or systematic position is inconsistent among different researchers[12,13,14,15,16]. We describe a new sauropodiform taxon excavated from the Chuanjie Basin in Lufeng County, about 22 km south and lightly west to Shawan, which is one of the classic dinosaur localities in the Lufeng Basin (Fig. 1B). This specimen is represented by an articulated skeleton with an exquisite skull and mandible preserved www.nature.com/scientificreports/. Our phylogenetic analysis indicates that this new taxon is located in the heart of the sauropodiform-sauropod transformation, shedding new light on the radiation of sauropodiforms before the origin of sauropods

Methods

Results

Conclusion