The first description of Rhinocerotidae (Perissodactyla, Mammalia) from Xinyaozi Ravine in Shanxi, North China

DONG Wei, BAI Wei-Peng, ZHANG Li-Min

Vertebrata Palasiatica 2021, 59 (4): 273-294. DOI: 10.19615/j.cnki.2096-9899.210715

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Abundant mammalian fossils were uncovered during the field exploration for Nihewan beds at the beginning of the 1980s along Xinyaozi Ravine at Nangaoya Township of Tianzhen County, Shanxi Province in North China and the studied taxa indicate an age of the early Early Pleistocene. Recent studies on the rhino material not yet described show that there are at least two species of rhinocerotids: Elasmotherium peii and Coelodonta nihowanensis . There might be a third taxon provisionally named as Stephanorhinus cf. S. kirchbergensis due to incompleteness of the specimens. Since its morphometric characters are between S. kirchbergensis and C. nihowanensis , it might be a variety of one of the two species although it is more similar to the former than the latter. In the same way, The rhino specimens from Xiashagou named as Rhinoceros sinensis (?) by Teilhard de Chardin and Piveteau (1930) might be a variety of S. kirchbergensis or C. nihowanensis . The rhinocerotids uncovered so far from the Early Pleistocene deposits in the generalized Nihewan Basin including two certain species and two uncertain ones. The localities yielding E. peii include Xiashagou, Shanshenmiaozhui, Daheigou and Xinyaozi; those yielding C. nihowanensis include Xiashagou, Danangou, Donggutuo, Shanshenmiaozhui and Xinyaozi. R. sinensis (?) appeared only at Xiashagou and Stephanorhinus cf. S. kirchbergensis only at Xinyaozi.

Comparison and determination The described specimen V 27430.1 with DP1-4 is characterized by the undulation of ectoloph, closure of medifossette; crochet, crista, paracone rib and metacone rib, parastyle and metastyle are well developed. The lower deciduous cheek teeth V 27430.2-3 by the presence of protoconid rib and undulation of protolophid and hypolophid. These traits distinguish them from those of S. kirchbergensis and they are the same as those from Shanshenmiaozhui and in accordance with the diagnosis of Coelodonta revised by Qiu et al. (2004). V 27430.1 is very close to the specimen reassigned to C. nihowanensis by Tong and Wang (2014) and that figured in fig. 3 of plate II by Teilhard de Chardin and Piveteau (1930), e.g. the undulation of buccal enamel of ectoloph, the closure of medifossette, absence of antecrochet, etc. Its dental dimensions are also close to those of C. nihowanensis from Xiashangou (Teilhard de Chardin and Piveteau, 1930), Shanshenmiaozhui (Tong and Wang, 2014), Longdan (Qiu et al., 2004), slightly different from those of C. antiquitatis from Dingcun (Pei, 1958) and West Europe (Guérin, 1980), somewhat different from those of S. kirchbergensis from Xinyaozi, Locs. 1 and 13 of Zhoukoudian (Table 5; Fig. 9). Both upper and lower dental dimensions of Xinyaozi specimens (Tables 5-6) are larger than those of C. tologoijensis from Transbaikalia (Beliajeva, 1966). The logarithm dimensions of upper deciduous cheek teeth comparison (Fig. 9) shows that those of V 27430.1 are the closest to those of C. nihowanensis from Longdan, then Xiashagou, and then Shanshenmiaozhui. Those of C. antiquitatis from Dingcun and S. kirchbergensis from Xinyaozi (V 27429.1) are also similar. And those of C. antiquitatis from West Europe are slightly smaller and those of S. kirchbergensis from Locs. 1 and 13 of Zhoukoudian are slightly larger.