Data matrix (in Nexus format) for the phylogenetic analysis from Amphipithecine primates are stem anthropoids: cranial and postcranial evidence

Since their discovery in 1927, the phylogenetic status of the Myanmar amphipithecines has been highly debated. These fossil primates are recognized either as anthropoids or as adapiform strepsirrhines. This uncertainty was largely the consequence of a limited fossil record consisting mostly of jaw fragments but lacking the critical cranial elements that might resolve this debate. We report here cranial remains associated with an ulna from a single individual pertaining to the amphipithecine <i>Ganlea megacanina</i>. In addition to anthropoid-like dentognathic characters, <i>Ganlea</i> displays several ulna and skull features that testify to its anthropoid affinities (e.g. short subvertically oriented lacrimal duct, lacrimal foramen and bone inside the orbit, maxillary contribution to the lower orbital rim, fused metopic suture). By contrast to crown anthropoids, however, <i>Ganlea</i> lacks postorbital closure, confirming that postorbital closure appeared later than many anthropoid dentognathic characters and evolved convergently in extant tarsiers and anthropoids. Thus, amphipithecines must now be recognized as stem anthropoids offering a unique window on the early evolution of cranial and skeletal features in anthropoids and reinforcing the hypothesis of an origin and early diversification of anthropoids in Asia.

自1927年被发现以来，缅甸Amphipithec类灵长类（amphipithecines）的系统发育地位（phylogenetic status）一直存在极大争议。这些化石灵长类要么被归类为类人猿（anthropoids），要么被归为兔猴型原猴类（adapiform strepsirrhines）。这种分类不确定性主要源于稀缺的化石记录：已发现的标本多为颌骨碎片（jaw fragments），缺乏可解决该争议的关键颅骨材料。本文报道了一件隶属于Amphipithec类<i>Ganlea megacanina</i>的单个个体的颅骨遗存，伴生有一块尺骨（ulna）。除具备类人猿样的牙颌特征（dentognathic characters）外，<i>Ganlea</i>还具有多项尺骨与颅骨形态特征，可证实其与类人猿的亲缘关系（例如：短且近垂直走向的泪管（lacrimal duct）、位于眼眶（orbit）内部的泪孔（lacrimal foramen）与泪骨、上颌骨（maxillary）参与构成眼眶下缘（lower orbital rim）、额中缝（metopic suture）完全愈合）。然而与冠群类人猿（crown anthropoids）不同，<i>Ganlea</i>不具有眶后闭合（postorbital closure）结构，这证实眶后闭合的出现时间晚于多数类人猿牙颌特征，且在现生跗猴（tarsiers）与类人猿中独立趋同演化而来。因此，Amphipithec类灵长类如今应被归为基干类人猿（stem anthropoids），为研究类人猿颅骨与骨骼特征的早期演化提供了独特视角，同时进一步支持了类人猿起源并早期分化于亚洲的假说。