Chaimanee Yaowalak, Yamee Chotima, Tian Pannipa, Khaowiset Kitti, Marandat Bernard, Tafforeau Paul, Nemoz Christian, Jaeger Jean-Jacques
Paleontological Section, Department of Mineral Resources, Bureau of Geological Survey, Bangkok 10400, Thailand.
Am J Phys Anthropol. 2006 Nov;131(3):311-23. doi: 10.1002/ajpa.20437.
A Khoratpithecus piriyai lower jaw corresponds to a well-preserved Late Miocene hominoid fossil from northeastern Thailand. Its morphology and internal structure, using a microcomputed tomography scan, are described and compared to those of other known Miocene hominoids. It originated from fluviatile sand and gravel deposits of a large river, and was associated with many fossil tree trunks, wood fragments, and large vertebrate remains. A biochronological analysis by using associated mammal fauna gives an estimated geological age between 9-6 Ma. The flora indicates the occurrence of a riverine tropical forest and wide areas of grassland. K. piriyai displays many original characters, such as the great breadth of its anterior dentition, suggesting large incisors, large lower M3, a canine with a flat lingual wall, and symphysis structure. Several of its morphological derived characters are shared with the orangutan, indicating sister-group relationship with that extant ape. This relationship is additionally strongly supported by the absence of anterior digastric muscle scars. These shared derived characters are not present in Sivapithecus, Ankarapithecus, and Lufengpithecus, which are therefore considered more distant relatives to the orangutan than Khoratpithecus. The Middle Miocene K. chiangmuanensis is older, displays more primitive dental characters, and shares several dental characters with the Late Miocene form. It is therefore interpreted as its probable ancestor. But its less enlarged M3 and more wrinkled enamel may suggest an even closer phylogenetic position to orangutan ancestors, which cannot yet be supported because of the incomplete fossil record. Thus Khoratpithecus represents a new lineage of Southeast Asian hominoids, closely related to extant great ape ancestors.
披披猴（Khoratpithecus piriyai）的下颌骨与来自泰国东北部保存完好的晚中新世类人猿化石相对应。利用微计算机断层扫描技术描述了其形态和内部结构，并与其他已知的中新世类人猿进行了比较。它源自一条大河的河流砂和砾石沉积物，与许多化石树干、木块和大型脊椎动物遗骸伴生。通过对伴生哺乳动物群进行生物年代学分析，估计其地质年龄在900万至600万年之间。植物群表明当时存在河流热带森林和大片草原。披披猴显示出许多原始特征，如前牙列宽度很大，表明有大的门齿、大的下第三磨牙、舌壁扁平的犬齿以及联合结构。它的一些形态衍生特征与红毛猩猩共有，表明与现存猿类有姐妹群关系。此外，没有前二腹肌疤痕有力地支持了这种关系。这些共同的衍生特征在西瓦古猿、安卡拉古猿和禄丰古猿中不存在，因此它们被认为是比披披猴与红毛猩猩关系更远的亲属。中新世中期的清迈披披猴（K. chiangmuanensis）年代更久远，显示出更原始的牙齿特征，并与晚中新世形态共有一些牙齿特征。因此，它被解释为其可能的祖先。但其第三磨牙不太增大且釉质皱纹更多，这可能表明它与红毛猩猩祖先的系统发育关系更密切，不过由于化石记录不完整，这一点尚未得到支持。因此，披披猴代表了东南亚类人猿的一个新谱系，与现存的大型猿类祖先密切相关。
