Friday, January 30, 2015

[Paleontology • 2015] Qijianglong guokr • A New Sauropod Dinosaur from the Late Jurassic of China and the Diversity, Distribution, and Relationships of Mamenchisaurids


Qijianglong guokr
Xing, Miyashita, Zhang, Li, Ye, Sekiya, Wang & Currie, 2015
Sauropod from Qijiang, Chongqing, China by CheungChungTat on @DeviantArt  DOI: 10.1080/02724634.2014.889701 

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.

Life restoration of Qijianglong
illustration: 
CheungChungTat on @DeviantArt

Systematic Palaeontology

SAURISCHIA Seeley, 1887
SAUROPODOMORPHA Huene, 1932

SAUROPODA Marsh, 1878
EUSAUROPODA Upchurch, 1995

MAMENCHISAURIDAE Young and Chao, 1972
Qijianglong, gen. nov.

Type and Only Known Species: Qijianglong guokr, sp. nov.

Etymology: Qijiang, after Qijiang District where the type specimen was collected and is accessioned; ‘long,’ dragon in Chinese. guokr (gu-OH-ke-r), named in honor of Guokr (science social network; ‘nutshell’ in Chinese) for their support of paleontology in Qijiang.


Lida Xing, Tetsuto Miyashita, Jianping Zhang, Daqing Li, Yong Ye, Toru Sekiya, Fengping Wang and Philip J. Currie. 2015. A New Sauropod Dinosaur from the Late Jurassic of China and the Diversity, Distribution, and Relationships of Mamenchisaurids.  Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2014.889701  



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