A new sauropod dinosaur from the Late Jurassic of China and the diversity, distribution, and relationships of mamenchisaurids

Abstract

ABSTRACT—Qijianglong guokr, gen. et sp. nov., represents a mamenchisaurid eusauropod from the Late Jurassic of southern China. The holotype consists of an incomplete skull, partly articulated axial skeleton, and fragmentary appendicular skeleton. A well-preserved braincase and skull roof provide rare insights into the poorly known neurocranial anatomy of mamenchisaurids and reveal a unique combination of characters such as an accessory tuber at the base of planar basipterygoid process and parietal excluding frontal from the anterior margin of the supratemporal fenestra. The cervical vertebrae have a distinct finger-like process extending from the postzygapophyseal process beside a zygapophyseal contact. Qijianglong is the first mamenchisaurid from the Late Jurassic of China that is definitively distinct from Mamenchisaurus, indicating greater morphological and taxonomic diversity of the poorly represented Late Jurassic mamenchisaurids. The occurrence of Qijianglong is consistent with a scenario in which mamenchisaurids formed an endemic sauropod fauna in the Late Jurassic of Asia. Phylogenetically, Qijianglong represents a relatively plesiomorphic mamenchisaurid lineage. The mamenchisaurids form an ancient clade of basal eusauropod dinosaurs that likely appeared in the Early Jurassic. A cladistic analysis highlights the interrelationships of mamenchisaurids and suggests guidelines for mamenchisaurid taxonomic revision. It may be desirable to restrict generic names to the type species in order to avoid confusion.

http://zoobank.org/urn:lsid:zoobank.org:pub:F93276CF-71FE-472E-9114-68294547C2A9

SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

ACKNOWLEDGMENTS

The authors thank directors, collections managers, and curators at numerous institutions that they visited for this project. T.M. especially thanks those at the Institute of Vertebrate Paleontology and Paleoanthropology, Zigong Dinosaur Museum, and Qijiang Petrified Wood and Dinosaur Footprint National Geological Park Museum (China) for access to specimens in their care and for their hospitality. O. Mateus (Universidade Nova de Lisboa, Portugal), J. D. Harris (Dixie State College, U.S.A.), E. B. Koppelhus, K. Miyashita, and W. S. Persons (University of Alberta, Canada), P. Upchurch (University College London, U.K.), J. A. Wilson (University of Michigan, U.S.A.), and H.-L. You (Institute of Geology, China) provided discussion, data sets, and/or logistic support. A. Paulina Carabajal and O. Wings provided careful reviews, and P. Druckenmiller and H.-L. You's attention to detail improved the style and presentation of the manuscript. Financial aid for this project came from Qijiang County Bureau of Land and Resources, Chongqing, China (to L.X.), Vanier CGS and Alberta Innovates PGS (to T.M.), and NSERC (to P.J.C.). Author contributions: L.X., J.Z., D.L., and F.W. conducted the field work and did the initial research. T.M. and L.X. executed description and comparison. L.X., T.M., J.Z., D.L., Y.Y., T.S., F.W., and P.J.C. provided materials and analytical tools. T.M., L.X., and P.J.C. drafted the manuscript.

Handling editor: You Hailu.