Oldest known euarchontan tarsals and affinities of Paleocene Purgatorius to Primates
Oldest known euarchontan tarsals and affinities of Paleocene Purgatorius to Primates
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DOI：
10.1073/pnas.1421707112
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发表时间：
2015-02-03
影响因子：
11.1
通讯作者：
Clemens, William A.
中科院分区：
文献类型：
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作者：
Chester, Stephen G. B.;Bloch, Jonathan I.;Clemens, William A.
最早的古新世炼狱通常被认为是地质学上最古老的灵长类动物，但自从半个世纪前首次描述它以来，人们只能从牙齿化石中了解它。炼狱兽的牙齿比所有已知的现存和化石灵长类动物的牙齿更原始，这使得一些研究人员认为它的祖先接近所有其他灵长类动物；然而，其他人质疑它与灵长类动物甚至胎盘哺乳动物的亲缘关系。在这里，我们报告了第一个（据我们所知）被认为属于炼狱兽的非牙齿遗骸（跗骨），这些遗骸来自最早的古新世沉积物，这些沉积物已经产生了这种鲜为人知的哺乳动物的大量牙齿化石。三个独立的系统发育分析结合了这些化石的新数据，支持了炼狱在原始哺乳动物（灵长类动物、树鼩和鼯猴）中的灵长类亲缘关系。来自Purgatorius的黄芪和足跖显示了一种典型的树栖原生哺乳动物的活动踝关节，特别是古新世和始新世的蛇适应动物，为灵长类动物和其他原生哺乳动物的树栖性提供了最早的化石证据。最早的灵长类动物对树栖的后颅特化可能在古新世哺乳动物辐射的进化成功中发挥了关键作用。
Earliest Paleocene Purgatorius often is regarded as the geologically oldest primate, but it has been known only from fossilized dentitions since it was first described half a century ago. The dentition of Purgatorius is more primitive than those of all known living and fossil primates, leading some researchers to suggest that it lies near the ancestry of all other primates; however, others have questioned its affinities to primates or even to placental mammals. Here we report the first (to our knowledge) nondental remains (tarsal bones) attributed to Purgatorius from the same earliest Paleocene deposits that have yielded numerous fossil dentitions of this poorly known mammal. Three independent phylogenetic analyses that incorporate new data from these fossils support primate affinities of Purgatorius among euarchontan mammals (primates, treeshrews, and colugos). Astragali and calcanei attributed to Purgatorius indicate a mobile ankle typical of arboreal euarchontan mammals generally and of Paleocene and Eocene plesiadapiforms specifically and provide the earliest fossil evidence of arboreality in primates and other euarchontan mammals. Postcranial specializations for arboreality in the earliest primates likely played a key role in the evolutionary success of this mammalian radiation in the Paleocene.