Table of Content

20 July 2020, Volume 58 Issue 3

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Osteological re-description of Macrocnemus fuyuanensis (Archosauromorpha, Tanystropheidae) from the Middle Triassic of China

Torsten M. SCHEYER, WANG Wei, LI Chun, Feiko MIEDEMA, Stephan N. F. SPIEKMAN

2020, 58(3):  169-187.  DOI: 10.19615/j.cnki.1000-3118.200525

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Over the past decades, an increasing number of reptiles have been described from the Middle Triassic of southern parts of China. Marine reptiles such as thalattosaurs, ichthyosaurs and sauropterygians dominated these paleofaunas and are known to have had a Tethys-wide distribution. Indeed, several species have been described from both the eastern and western margins of that ancient ocean. The last addition to this list was a less common terrestrial reptile, Macrocnemus fuyuanensis, first discovered in Yunnan Province. The species was also tentatively inferred to be represented by a single disarticulated specimen in the paleofauna from the World Heritage Site of Monte San Giorgio in southern Switzerland (as Macrocnemus aff. fuyuanensis). The initial referral was mainly based on limb proportions and ratios rather than on discrete osteological characters, partially due to a limited anatomical description of the holotype specimen of M. fuyuanensis. Here we provide a re-description of the anatomy of the complete skeleton of the holotype and compare it with the available referred specimens. Our re-analysis shows that the pectoral girdle of the holotype specimen is more complete than previously reported, revealing the shape of the interclavicle, which is only partially exposed in the only referred specimen from China but well-preserved in the specimen from Europe. The interclavicle of M. fuyuanensis can be distinguished from M. bassanii by its short and fusiform posterior process and anterior facing rod-like processes that extend from a common base enclosing a narrow V-shaped median notch, among other features, and is here inferred to be the most important bone for discriminating species of Macrocnemus, apart from the limb ratios. We further document in detail the cranial anatomy of the holotype, which is virtually identical to that of the crania of M. bassanii, and due to its exquisite preservation and preparation, it adds important information on the palate, which was previously poorly known for Macrocnemus.

A new species of Amynodontopsis (Perissodactyla: Amynodontidae) from the Middle Eocene of Jiyuan, Henan, China

WANG Xiao-Yang, WANG Yuan-Qing, ZHANG Rui, ZHANG Zhong-Hui, LIU Xiao-Ling, REN Li-Ping

2020, 58(3):  188-203.  DOI: 10.19615/j.cnki.1000-3118.200313

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An adult amynodont skull, collected from the Middle Eocene Niezhuang Formation of Jiyuan Basin (Henan, China), is recognized as a new species Amynodontopsis jiyuanensis sp. nov. The specimen possesses the typical features of the genus Amynodontopsis, such as a dolichocephalic skull with elevated roof, premaxilla-nasal contact, large preorbital fossa extending posteriorly medial to the orbit, inner surface of anterior orbital bar concave in continuation with the preorbital fossa, antecrochet usually presented on M1, and metastyle of M3 strongly deflected labially. Amynodontopsis jiyuanensis is diagnosed by a combination of the following characters: long nasals, nasal process of premaxilla extending far back laterally below the nasal and excluding the maxilla from the border of external nares, nasal notch above the post-canine diastema, more transverse and proportionally longer protoloph and metaloph on upper molars. Comparison with known species of Amynodontopsis indicates that it is the most primitive one in the genus, due to the possession of primitive characters. Associated fossil mammals support a correlation of the strata bearing A. jiyuanensis with the Shara Murun Formation of the Erlian Basin, Nei Mongol, China, namely the Middle Eocene Sharamurunian Asian Land Mammal Age (ALMA), prior to all other known Amynodontopsis species. The earlier geologic age and primitive morphological features of A. jiyuanensis suggest that Amynodontopsis has an Asian origin in the Middle Eocene and later immigrated into North America.

New Hystrix (Hystricidae, Rodentia) from the Neogene of Linxia Basin, Gansu, China

WANG Ban-Yue, QIU Zhan-Xiang

2020, 58(3):  204-220.  DOI: 10.19615/j.cnki.1000-3118.200514

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Four well preserved skulls of Hystrix recently collected from Linxia Basin were studied and a new species, H. brevirostra sp. nov, was established for them. The new species is characterized by its larger size, relatively low and wide skull with short rostrum and diastema, slightly posteriorly convex posterior border of relatively short nasal roughly aligning with lacrimal, shorter and deeply curved mandibular diastema, and relatively low-crowned cheek teeth. It is intermediate between H. lufengensis and H. gansuensis in evolutionary level, existing in Late Miocene-Pliocene. While it might represent a lineage separated from the above two species. Ontogenetic variation in skull morphology and direction of cheek tooth rows of the new species was also discussed.

New material of Cervidae (Artiodactyla, Mammalia) from Xinyaozi Ravine in Shanxi, North China

DONG Wei, BAI Wei-Peng, PAN Yue, LIU Wen-Hui

2020, 58(3):  221-248.  DOI: 10.19615/j.cnki.1000-3118.200320

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Many cervid specimens were uncovered during the field exploration for Nihewan beds at the beginning of the 1980s from Taijiaping, Shuichongkou and Dazhuangke localities along Xinyaozi Ravine at Nangaoya Township of Tianzhen County, Shanxi Province in North China. Recent studies on the cervid material identified seven species of Cervidae in total: Muntiacus bohlini, Cervavitus cf. C. huadeensis, Axis shansius, Nipponicervus elegans, Elaphurus davidianus predavidianus, E. bifurcatus from the Early Pleistocene deposits at Taijiaping and Shuichongkou localities, and Cervus (Elaphus) elaphus from uncertain horizon at Dazhuangke. At least the previous six species of cervids were from Nihewan Formation (Nihewanian or equivalent to European middle and late Villafranchian), i.e. the Early Pleistocene, in Sangganhe Basin area. Cervavitus cf. C. huadeensis and A. shansius were survivors from the Late Neogene; M. bohlini, N. elegans, E. davidianus predavidianus and E. bifurcatus are new forms of the Early Pleistocene. If Dazhuangke horizon can be dated as those of Shuichongkou and Taijiaping localities, the appearance of elaphoid cervids could be traced back to the Early Pleistocene, and the evolution of elaphoid antler would start from absence to presence of bez tine. The presence of Elaphurus and Nipponicervus in mainland China and Japanese archipelago implies further that the sea level was dropped down that these cervids could migrate from the mainland to the islands. The abundance of folivorous cervid specimens in the Xinyaozi Ravine area indicates the existence of a certain scale of forested environment in Sangganhe Basin area during the Early Pleistocene.