Seiffert Erik R, Simons Elwyn L, Boyer Doug M, Perry Jonathan M G, Ryan Timothy M, Sallam Hesham M
Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794-8081, USA.
Proc Natl Acad Sci U S A. 2010 May 25;107(21):9712-7. doi: 10.1073/pnas.1001393107. Epub 2010 May 10.
Paleontological work carried out over the last 3 decades has established that three major primate groups were present in the Eocene of Africa-anthropoids, adapiforms, and advanced strepsirrhines. Here we describe isolated teeth of a previously undocumented primate from the earliest late Eocene ( approximately 37 Ma) of northern Egypt, Nosmips aenigmaticus, whose phylogenetic placement within Primates is unclear. Nosmips is smaller than the sympatric adapiform Afradapis but is considerably larger than other primate taxa known from the same paleocommunity. The species bears an odd mosaic of dental features, combining enlarged, elongate, and molariform premolars with simple upper molars that lack hypocones. Phylogenetic analysis across a series of different assumption sets variously places Nosmips as a stem anthropoid, a nonadapiform stem strepsirrhine, or even among adapiforms. This phylogenetic instability suggests to us that Nosmips likely represents a highly specialized member of a previously undocumented, and presumably quite ancient, endemic African primate lineage, the subordinal affinities of which have been obscured by its striking dental autapomorphies. Discriminant functions based on measurements of lower molar size and topography reliably classify extant prosimian primates into their correct dietary groups and identify Nosmips and Afradapis as omnivores and folivores, respectively. Although Nosmips currently defies classification, this strange and unexpected fossil primate nevertheless provides additional evidence for high primate diversity in northern Africa approximately 37 million years ago and further underscores the fact that our understanding of early primate evolution on that continent remains highly incomplete.
过去30年开展的古生物学研究已证实，在非洲始新世存在三大灵长类动物群体——类人猿、兔猴型类和进步的原猴亚目。在此，我们描述了一种此前未被记录的灵长类动物的单独牙齿，它来自埃及北部最早的晚始新世（约3700万年前），名为神秘诺氏猴（Nosmips aenigmaticus），其在灵长目内的系统发育位置尚不清楚。诺氏猴比同域分布的兔猴型类阿法达皮猴（Afradapis）小，但比来自同一古群落的其他灵长类分类单元大得多。该物种具有奇特的牙齿特征组合，其前磨牙增大、拉长且呈臼齿状，而上臼齿简单，没有下后尖。在一系列不同假设集下进行的系统发育分析，将诺氏猴置于不同位置，它可能是类人猿主干、非兔猴型类原猴亚目主干，甚至在兔猴型类之中。这种系统发育的不稳定性让我们觉得，诺氏猴可能代表了一个此前未被记录且可能相当古老的非洲特有灵长类谱系中的高度特化成员，其亚目亲缘关系因显著的牙齿自近裔性状而变得模糊不清。基于下臼齿大小和形态测量的判别函数能够可靠地将现存的原猴亚目灵长类动物正确归类到它们的饮食类别中，并将诺氏猴和阿法达皮猴分别鉴定为杂食动物和食叶动物。尽管诺氏猴目前难以归类，但这种奇特且出人意料的化石灵长类动物仍然为约3700万年前北非灵长类动物的高度多样性提供了额外证据，并进一步强调了我们对该大陆早期灵长类动物进化的理解仍然非常不完整这一事实。
