New material of <i>Miotragocerus</i> (Bovidae, Artiodactyla) from northern China and its systematic implications

Late Miocene tragoportacins are widespread in Eurasia and Africa and are important members of the Hipparion fauna. The phylogenetic relationships within the tragoportacins are debatable due to the large number of species, fragmentary materials, and large intraspecific variations. The Chinese tragoportacins are rare and poorly studied in previous work. Recently, a dozen well-preserved skulls were excavated from northern China, providing important information for the classification and phylogenetic analysis of the Chinese tragoportacins. In this study, we assign the new material from Linxia Basin and Fugu County to Miotragocerus gregarius, providing detailed descriptions of both males and females. We discuss sexual dimorphism and compare the horn core, dentition and cranium characters in Miotragocerus, Tragoportax and related species. We also perform cladistic analyses, including Eurasian and African tragoportacins, Tetracerus and Eotragus. The phylogenetic analysis indicates that the two Chinese late Miocene tragoportacins belong to Miotragocerus and Tragoportax, which immigrated from the west to China in different periods.晚中新世的Tragoportax类（tragoportacins）广布于欧亚大陆与非洲，是三趾马动物群（Hipparion fauna）的重要组成类群。由于该类群物种数量繁多、化石材料残缺且种内变异幅度较大，其内部的系统发育关系一直存在争议。此前针对中国境内Tragoportax类的研究较为薄弱，相关化石记录也较为稀少。近期，科研人员从中国北方地区发掘出十余件保存完好的头骨化石，为中国境内Tragoportax类的分类与系统发育研究提供了关键资料。本研究将产自临夏盆地与府谷县的这批新材料归入葛氏近鹿（Miotragocerus gregarius），并对该物种的雌雄个体标本均进行了详细描述。本研究探讨了该类群的性别二态性，并对比了近鹿属（Miotragocerus）、Tragoportax属及相关类群的角心、齿列与颅骨特征。此外，本研究还开展了分支系统学分析，涵盖的类群包括欧亚大陆与非洲的Tragoportax类、四角鹿属（Tetracerus）以及始鹿属（Eotragus）。系统发育分析结果显示，中国境内发现的晚中新世Tragoportax类类群分别隶属于近鹿属（Miotragocerus）与Tragoportax属，二者均从西方迁徙至中国，且各自的迁徙时期存在差异。