Dunn Rachel H, Sybalsky Julia M, Conroy Glenn C, Rasmussen D Tab
Department of Anthropology, Washington University, St. Louis, Missouri 63130, USA.
Am J Phys Anthropol. 2006 Nov;131(3):303-10. doi: 10.1002/ajpa.20407.
North American omomyids represent a tremendous Eocene radiation of primates exhibiting a wide range of body sizes and dietary patterns. Despite this adaptive diversity, relatively little is known of the postcranial specializations of the group. Here we describe hindlimb and foot bones of Ourayia uintensis and Chipetaia lamporea that were recovered from the Uinta B member (early Uintan Land Mammal Age), Uinta Formation, Utah. These specimens provide insights into the evolution of postcranial adaptations across different body sizes and dietary guilds within the Eocene primate radiation. Body mass estimates based on talar measurements indicate that Ourayia uintensis and Chipetaia lamporea weighed about 1,500-2,000 g and 500-700 g, respectively. Skeletal elements recovered for Ourayia include the talus, navicular, entocuneiform, first metatarsal, and proximal tibia; bones of Chipetaia include the talus, navicular, entocuneiform, and proximal femur. Both genera had opposable grasping big toes, as indicated by the saddle-shaped joint between the entocuneiform and first metatarsal. Both taxa were arboreal leapers, as indicated by a consistent assemblage of characters in all represented bones, most notably the somewhat elongated naviculars, the high and distinct trochlear crests of the talus, the posteriorly oriented tibial plateau (Ourayia), and the cylindrical head of the femur (Chipetaia). The closest resemblances to Ourayia and Chipetaia are found among the Bridger omomyines, Omomys and Hemiacodon. The results of our comparisons suggest that the later, larger, more herbivorous omomyines from Utah retained a skeletal structure characteristic of earlier, smaller North American omomyids.
北美始新世眼镜猴科动物代表了灵长类动物在始新世的一次巨大辐射，展现出广泛的体型和饮食模式。尽管存在这种适应性多样性，但对于该类群的颅后特化却知之甚少。在此，我们描述了从犹他州尤因塔组Uinta B段（早尤因塔期陆地哺乳动物时代）发现的尤因塔奥雷眼镜猴（Ourayia uintensis）和兰氏奇佩塔眼镜猴（Chipetaia lamporea）的后肢和足部骨骼。这些标本为始新世灵长类动物辐射中不同体型和食性类群的颅后适应性演化提供了见解。基于距骨测量的体重估计表明，尤因塔奥雷眼镜猴和兰氏奇佩塔眼镜猴的体重分别约为1500 - 2000克和500 - 700克。为尤因塔奥雷眼镜猴找到的骨骼元素包括距骨、舟骨、内楔骨、第一跖骨和胫骨近端；奇佩塔眼镜猴的骨骼包括距骨、舟骨、内楔骨和股骨近端。如内楔骨与第一跖骨之间的鞍状关节所示，这两个属都有可对握抓握的大脚趾。如所有呈现骨骼中一致的特征组合所示，这两个分类单元都是树栖跳跃者，最显著的是舟骨略显细长、距骨的滑车嵴高且明显、尤因塔奥雷眼镜猴的胫骨平台向后倾斜以及奇佩塔眼镜猴的股骨头部呈圆柱形。与尤因塔奥雷眼镜猴和奇佩塔眼镜猴最相似的是布里杰眼镜猴亚科的奥莫鼠属（Omomys）和半犬齿猴属（Hemiacodon）。我们的比较结果表明，来自犹他州的体型更大、更食草的较晚眼镜猴亚科动物保留了早期体型较小的北美眼镜猴科动物的骨骼结构特征。
