Analysis of the teeth, orbital, and gnathic regions of the skull, and fragmentary postcranial bones provides evidence for reconstructing a behavioral profile of Amphipithecidae: Pondaungia, Amphipithecus, Myanmarpithecus (late middle Eocene, Myanmar) and Siamopithecus (late Eocene, Thailand). At 5-8 kg, Pondaungia, Amphipithecus, and Siamopithecus are perhaps the largest known Eocene primates. The dental and mandibular anatomy suggest that large-bodied amphipithecids were hard-object feeders. The shape of the mandibular corpus and stiffened symphysis suggest an ability to resist large internal loads during chewing and to recruit significant amounts of muscle forces from both the chewing and non-chewing sides of the jaw so as to increase bite force during mastication. The large spatulate upper central incisor of Pondaungia and projecting robust canines of all the larger amphipithecids suggest that incisal food preparation was important. The molars of Siamopithecus, Amphipithecus, and Pondaungia have weak shearing crests. This, and the thick molar enamel found in Pondaungia, suggests a diet of seeds and other hard objects low in fiber. In contrast, Myanmarpithecus was smaller, about 1-2 kg; its cheek teeth suggest a frugivorous diet and do not imply seed eating. Postcranial bones (humerus, ulna, and calcaneus) of a single large amphipithecid individual from Myanmar suggest an arboreal quadrupedal locomotor style like that of howler monkeys or lorises. The humeral head is rounded, proximally oriented, and the tuberosities are low indicating an extremely mobile glenohumeral joint. The great thickness of the midshaft cortical bone of the humerus implies enhanced ability to resist bending and torsion, as seen among slow moving primate quadrupeds. The elbow joint exhibits articular features for enhanced stability in habitually flexed positions, features also commonly found in slow moving arboreal quadrupeds. The short distal load arm of the calcaneus is consistent with, but not exclusive to, slow, arboreal quadrupedalism, and suggests no reliance on habitual leaping.

中文翻译：

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南亚始新世晚灵长类动物两栖类科的古生物学。

对头骨的牙齿，眼眶和咬骨区域以及颅后碎骨的分析为重建两栖类科的行为特征提供了证据：P虫，两栖类，缅甸属（始新世中期，缅甸）和暹粒（始新世末期，泰国）。重量为5-8公斤的Pondaungia，amphipithecus和Siamopithecus可能是已知最大的始新世灵长类动物。牙齿和下颌的解剖结构表明，大型两栖类动物是硬物饲养者。下颌骨的形状和僵化的联合体表明，在咀嚼过程中能够抵抗较大的内部负荷，并能从颚的咀嚼和非咀嚼侧吸收大量的肌肉力，从而在咀嚼时增加咬合力。Pondaungia的大齿状上中切牙和所有较大的两栖类动物的突出犬齿表明切开食物的准备很重要。Siamopithecus，amphipithecus和Pondaungia的臼齿具有较弱的剪切波峰。这以及在Pondaungia中发现的厚磨牙珐琅质，建议饮食中少吃种子和其他纤维含量低的硬物。相反，缅甸上皮较小，约为1-2公斤；它的颊齿暗示节食，并不意味着要吃种子。一个来自缅甸的大型两栖动物个体的颅后骨头（肱骨，尺骨和跟骨）显示出树栖的四足动物运动风格，如吼猴或懒猴。肱骨头呈圆形，朝近侧，结节低，表明盂肱关节极为活动。在缓慢移动的灵长类四足动物中可以看到，肱骨的中轴皮质骨的较大厚度意味着增强的抵抗弯曲和扭转的能力。肘关节在惯常屈曲的位置表现出增强的稳定性的关节特征，这种特征在缓慢移动的四足动物四足动物中也很常见。跟骨的远端远端短臂与缓慢的树栖四足动物是一致的，但并非排他性的，并不暗示它依赖于惯常的跳跃。