Table of Content

20 April 2019, Volume 57 Issue 2

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The posterior cranial portion of the earliest known tetrapodomorph Tungsenia paradoxa and the early evolution of tetrapodomorph endocrania

LU Jing, Gavin YOUNG, HU Yu-Zhi, QIAO Tuo, ZHU Min

2019, 57(2):  93-104.  DOI: 10.19615/j.cnki.1000-3118.181031

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Here the posterior cranial portion of the tetrapodomorph Tungsenia from the Lower Devonian (Pragian, ~409 million years ago) of Yunnan, southwest China, is reported for the first time. The pattern of posterior skull roof and the morphology of the otoccipital region of the neurocranium are described in detail, providing precious insight into the combination of cranial characters of the earliest known tetrapodomorph to date. The posterior cranium of Tungsenia displays a mosaic of features previously linked either to basal dipnomorphs such as Youngolepis (e.g., the well-developed subjugular ridge, the strong adotic process, and the poorly developed fossa bridgei) or to typical tetrapodomorphs (e.g., the lateral dorsal aortae commenced from the median dorsal aorta postcranially). The independent ventral arcual plate is also found in the advanced tetrapodomorph Eusthenopteron. The new endocranial material of Tungsenia further fills in the morphological gap between Tetrapodomorpha (tetrapod lineage) and Dipnomorpha (lungfish lineage) and unveils the sequence of character acquisition during the initial diversification of the tetrapod lineage. The new phylogenetic analysis strongly supports the basalmost position of Tungsenia amongst the tetrapod lineage.

Discovery of Omeisaurus (Dinosauria: Sauropoda) in the Middle Jurassic Shaximiao Formation of Yunyang, Chongqing, China

TAN Chao, DAI Hui, HE Jian-Jun, ZHANG Feng, HU Xu-Feng, YU Hai-Dong, LI Ning, WEI Guang-Biao, PENG Guang-Zhao, YE Yong, ZHANG Qian-Nan, REN Xin-Xin, YOU Hai-Lu

2019, 57(2):  105-116.  DOI: 10.19615/j.cnki.1000-3118.181115

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A cervical vertebra recovered from the Middle Jurassic Lower Member of the Shaximiao Formation in Town of Puan, Yunyang County, Chongqing is assigned to an species undeterminata of the sauropod dinosaur Omeisaurus based on morphological and comparative study. The centrum of this mid-cervical is much hollower than solider with extremely developed fossa/foramen complex and has a high ratio (5.05) of its anteroposterior length excluding the articular ball divided by the mean value of the posterior articular surface mediolateral width and dorsoventral height. Additional features of this cervical include central length about twice the total vertebral height, a prominent midline keel on the central ventral surface, deep and long cavities bounded by centroprezygapophyseal lamina/ intraprezygapophyseal lamina and centropostzygapophyseal lamina/intrapostzygapophyseal lamina, respectively, a coel on the dorsal half of the postzygapophyseal centrodiapophyseal fossa, long prone epipophysis extending beyond the postzygapophysis facet, anteroposteriorly length of the neural spine about half the length of the centrum, and concavities on the anterior one third lateral surface of the neural spine. Therefore, this discovery reveals new morphological information on Omeisaurus, and this Omeisaurus-bearing Puan dinosaur quarry represents the easternmost occurrence of this genus.

Cranial osteology of Beipiaosaurus inexpectus(Theropoda: Therizinosauria)

LIAO Chun-Chi, XU Xing

2019, 57(2):  117-132.  DOI: 10.19615/j.cnki.1000-3118.190115

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Beipiaosaurus inexpectus, a key taxon for understanding the early evolution of therizinosaurians, has not been fully described since it was briefly reported on by Xu, Tang and Wang in 1999. Here we present a detailed description of the cranial anatomy of the holotype of this theropod dinosaur. B. inexpectus is unique in some of its cranial features such as the postorbital process of the frontal is large and its abrupt transition from the orbital rim, a long and sharp anterior process of the parietal, the elongate ventral ramus of the squamosal process of parietal, and external mandibular fenestra deep dorsoventrally and extremely posteriorly located. A number of plesiomorphic cranial features (such as relatively large dentary and less downturned degree of dentary symphysis) suggest that B. inexpectus is an early-branching Therizinosaurian, as proposed by previous studies. New information derived from our study is not only important for our understanding of the cranial anatomy of B. inexpectus but also significant to the study of the evolution of Therizinosauria.

A record of the early Protanancus and Stephanocemas from the north of the Junggar Basin, and its implication for the Chinese Shanwangian

WANG Shi-Qi, LI Chun-Xiao, ZHANG Xiao-Xiao, JIANGZUO Qi-Gao, YE Jie, LI Lu, LI Fu-Chang

2019, 57(2):  133-154.  DOI: 10.19615/j.cnki.1000-3118.181108

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The Chinese Neogene mammalian fauna sequence has been well established, except for a gap in the early Shanwangian (~20-18 Ma) for which there are few known records of fossil mammals in China. Hereby we report on a newly discovered fossiliferous horizon from the upper part of the Suosuoquan Formation (18.6 Ma), Chibaerwoyi East locality, northern Junggar Basin, Xinjiang Uyghur Autonomous Region. In this locality, the occurrences of an early Eurasian proboscidean and an early cervid clearly indicate an early Shanwangian Age of the Early Miocene. The proboscidean check teeth are characterized by the well-developed posttrite trefoils on the second lophs. It was identified as Protanancus sp. (Amebelodontidae), which is morphologically more primitive than the late Shanwangian P. brevirostris and P. tobieni. The cervid antler is characterized by the relatively small yet high palm of the antler and relatively short tines. It was identified as Stephanocemas sp. (Lagomerycinae), which is phylogenetically very close to the dichotomy of Stephanocemas and Lagomeryx, and is morphologically close to the more ancestral Ligeromeryx. Previous studies have shown that both proboscideans and cervids occurred at the Xiejian/Shanwangian transition period. Therefore, the new materials of Protanancus sp. and Stephanocemas sp. give important clues to the first appearance data of proboscideans and cervids in this area, which facilitates establishing the lower stratotype of the Chinese Shanwangian. In conclusion, the new findings represent a rarely known stage of mammalian biostratigraphy in China and are helpful for understanding the faunal succession during the early Chinese Shanwangian.

A new species of Kubanochoerus (Suidae, Artiodactyla) from the Linxia Basin, Gansu Province, China

HOU Su-Kuan, DENG Tao

2019, 57(2):  155-172.  DOI: 10.19615/j.cnki.1000-3118.180402

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A new specimen of kubanochoeres has been discovered from the Maida locality, Linxia Basin, Gansu Province, China, and a new species, Kubanochoerus parvus sp. nov., has been created based on the unique partially broken cranium. The new species has a relatively small body size similar to K. massai and K. minheensis. The new species, which possesses relatively wide cheek teeth that resemble those of K. massai and many derived characters that are similar to K. gigas, may represent a separate lineage of the Eurasian kubanochoeres. The horizon of the Maida locality is speculated to be the upper Hujialiang Formation or lower Liushu Formation, and the new species is possibly the youngest known kubanochoere. Based on the comparison of the known kubanochoere, Libycochoerus is suggested to be a synonym of Kubanochoerus, while K. robustus and K. lantienensis are synonyms of K. gigas. There is not sufficient evidence to support the subdivision of K. gigas at the subspecies level. Kubanochoerus gigas is speculated to have derived from more primitive forms that existed earlier than K. massai, and the new species may be derived from K. massai or other earlier forms. Kubanochoerus minheensis, which bears a relatively small body size and rudimentary sub-lophodont dentition, is suggested to be another separate lineage of the Eurasian kubanochoeres.