Kunming Natural History Museum of Zoology, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650201, China; Department of Paleoanthropology, Yunnan Institute of Cultural Relics and Archaeology, Kunming, 650118, China.
Center for the Study of Human Origins, Department of Anthropology, New York University, New York, NY, 10003, USA.
J Hum Evol. 2022 Oct;171:103251. doi: 10.1016/j.jhevol.2022.103251. Epub 2022 Sep 13.
Yuanmoupithecus xiaoyuan, a small catarrhine from the Late Miocene of Yunnan in southern China, was initially suggested to be related to Miocene proconsuloids or dendropithecoids from East Africa, but subsequent reports indicated that it might be more closely related to hylobatids. Here, detailed comparisons of the material, including seven newly discovered teeth and a partial lower face of a juvenile individual, provide crucial evidence to help establish its phylogenetic relationships. Yuanmoupithecus exhibits a suite of synapomorphies that support a close phylogenetic relationship with extant hylobatids. Furthermore, based on the retention of several primitive features of the dentition, Yuanmoupithecus can be shown to be the sister taxon of crown hylobatids. The contention that Kapi ramnagarensis from the Middle Miocene of India might represent an earlier species of hylobatid is not supported here. Instead, Kapi is inferred to be a specialized pliopithecoid more closely related to Krishnapithecus krishnaii from the Late Miocene of India. Currently then, Yuanmoupithecus represents the earliest known definitively identified hylobatid and the only member of the clade predating the Pleistocene. It extends the fossil record of hylobatids back to 7-8 Ma and fills a critical gap in the evolutionary history of hominoids that has up until now remained elusive. Even so, molecular estimates of a divergence date of hylobatids from other hominoids at about 17-22 Ma signifies that there is still a substantial gap in the fossil record of more than 10 million years that needs to be filled in order to document the biogeographic origins and early evolution of hylobatids.
元谋小猿，一种来自中国云南晚中新世的小型简鼻猴，最初被认为与东非的中新世原猴或树猿类有关，但后来的报告表明它可能与长臂猿更为密切相关。在这里，对材料的详细比较，包括七个新发现的牙齿和一个幼年个体的部分下脸，提供了至关重要的证据来帮助建立其系统发育关系。元谋小猿表现出一系列的共形特征，支持与现生长臂猿密切的系统发育关系。此外，基于牙齿的几个原始特征的保留，元谋小猿可以被证明是冠长臂猿的姐妹分类群。这里不支持印度中中新世的卡皮拉玛纳加ensis 代表更早的长臂猿物种的观点。相反，卡皮被推断为一种更接近印度晚中新世的克里希纳皮氏长臂猿的特化的笔尾猴。目前，元谋小猿代表了已知最早的、明确鉴定的长臂猿，也是唯一早于更新世的类群成员。它将长臂猿的化石记录追溯到 7-8 Ma，并填补了人科进化史上一个关键的空白，而这个空白直到现在仍然难以捉摸。即便如此，分子估计表明，长臂猿与其他人科的分歧时间约为 17-22 Ma，这意味着在化石记录中仍然存在一个超过 1000 万年的巨大空白，需要填补，以记录长臂猿的生物地理起源和早期进化。
