Laboratory PALEVOPRIM, UMR 7262 CNRS, University of Poitiers, 6 rue Michel Brunet, 86073 Poitiers cedex 9, France.
Laboratory PALEVOPRIM, UMR 7262 CNRS, University of Poitiers, 6 rue Michel Brunet, 86073 Poitiers cedex 9, France.
J Hum Evol. 2019 Sep;134:102636. doi: 10.1016/j.jhevol.2019.06.007. Epub 2019 Jul 15.
The evolutionary history of Asian Miocene hominids (great apes and humans) remains poorly documented, obscuring the ancestry of orangutan (Pongo). Khoratpithecus from the middle and late Miocene of Thailand and Myanmar was previously documented only by mandibles and isolated teeth. It has been interpreted as the closest relative of Pongo based on shared derived mandible characters such as symphyseal morphology and the lack of anterior digastric muscle scars. Here we describe a new maxilla, MFT-K176, which originates from the same sedimentary unit as the holotype mandible of Khoratpithecus piriyai from the late Miocene in Nakhon Ratchasima province, Northeastern Thailand. The new maxilla displays a unique subnasal morphology with several derived characters being shared only with Sivapithecus and Pongo, confirming its attribution to the pongine clade. However, it differs from other known Asian hominids by it subnasal and dental morphology, showing more similar to Khoratpithecus chiangmuanensis teeth. Metric similarities with the mandible of K. piriyai corroborate the referral of MFT-K176 to Khoratpithecus. However, as associated upper and lower teeth would be required to evaluate the latter assertion more conclusively, we attribute it provisionally to cf. Khoratpithecus sp. Other anatomical characters from the clivus, the palate and the molars are peculiar for this hominid but do not exclude it from a sister group relationship with Pongo. This new maxilla plays a pivotal role in understanding that Ankarapithecus occupies a more basal position within the pongine clade and supports the exclusion of Lufengpithecus from this clade.
亚洲中新世古人类（大型猿类和人类）的进化史记录甚少，这使得猩猩（Pongo）的祖先情况变得模糊不清。来自泰国和缅甸中晚期中新世的科拉特猕猴（Khoratpithecus）以前仅通过下颌骨和孤立的牙齿记录在案。基于下颌骨形态相似性和缺乏前二腹肌肌痕等共享衍征，它被解释为猩猩的近亲。在这里，我们描述了一个新的上颌骨，MFT-K176，它源自泰国东北部那空叻差是玛府同沉积单元，与科拉特猕猴的正型标本来自同一沉积单元。新的上颌骨显示出独特的鼻下形态，具有几个仅与西瓦古猿和猩猩共享的衍生特征，这证实了它属于猩猩分支。然而，它与其他已知的亚洲古人类通过鼻下和牙齿形态而不同，显示出与科拉特猕猴更相似的特征。与科拉特猕猴的下颌骨的度量相似性证实了 MFT-K176 的归属。然而，由于需要上下牙齿才能更明确地评估后者的说法，我们暂时将其归因于 cf. Khoratpithecus sp. 来自犁骨、 palate 和臼齿的其他解剖特征对这种古人类来说是独特的，但不能排除其与猩猩具有姐妹群关系。这个新的上颌骨在理解安卡拉古猿在猩猩分支中占据更基础的位置方面发挥了关键作用，并支持将禄丰古猿排除在这个分支之外。
