最近对始新世原始灵长类Darwinius（或称“Ida”）的介绍引起了一阵骚动，因为有人称它是一个曾经“缺失的环节”，接近包括人类在内的类人猿（高等灵长类）的祖先。古生物学家对此有所担心，因为很少有人认为Darwinius所属的已灭绝的类别（即adapoids）接近类人猿。
现在，Erik Seiffert及其同事介绍了一个在埃及新发现的距今已有3700万年的adapoid（被命名为Afradapis）的颌骨和牙齿。虽然详细的系统发生分析表明，这一新形式（同Darwinius一样）与类人猿只是有远亲关系，但它的确有几个能够说明趋同进化的特征。可能的情况是，Darwinius 和Afradapis都是一个类别中的成员，这个类别在始新世中期趋同进化出一些与类人猿相似的适应性特征，但它们在始新世晚期和渐新世早期最终被真正的类人猿取代了。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 461, 1118-1121 (22 October 2009) | doi:10.1038/nature08429
Convergent evolution of anthropoid-like adaptations in Eocene adapiform primates
Erik R. Seiffert1, Jonathan M. G. Perry2, Elwyn L. Simons3 & Doug M. Boyer4
1 Department of Anatomical Sciences, Stony Brook University, Stony Brook, New York 11794-8081, USA
2 Department of Anatomy, Midwestern University, Downers Grove, Illinois 60515, USA
3 Division of Fossil Primates, Duke Lemur Center, 1013 Broad Street, Durham, North Carolina 27705, USA
4 Department of Ecology & Evolution, Stony Brook University, Stony Brook, New York 11794-5245, USA
5 Correspondence to: Erik R. Seiffert1 Correspondence and requests for materials should be addressed to E.R.S.
Adapiform or 'adapoid' primates first appear in the fossil record in the earliest Eocene epoch (55 million years (Myr) ago), and were common components of Palaeogene primate communities in Europe, Asia and North America1. Adapiforms are commonly referred to as the 'lemur-like' primates of the Eocene epoch, and recent phylogenetic analyses have placed adapiforms as stem members of Strepsirrhini2, 3, 4, a primate suborder whose crown clade includes lemurs, lorises and galagos. An alternative view is that adapiforms are stem anthropoids5. This debate has recently been rekindled by the description of a largely complete skeleton of the adapiform Darwinius 6, from the middle Eocene of Europe, which has been widely publicised as an important 'link' in the early evolution of Anthropoidea7. Here we describe the complete dentition and jaw of a large-bodied adapiform (Afradapis gen. nov.) from the earliest late Eocene of Egypt (37 Myr ago) that exhibits a striking series of derived dental and gnathic features that also occur in younger anthropoid primates—notably the earliest catarrhine ancestors of Old World monkeys and apes. Phylogenetic analysis of 360 morphological features scored across 117 living and extinct primates (including all candidate stem anthropoids) does not place adapiforms as haplorhines (that is, members of a Tarsius–Anthropoidea clade) or as stem anthropoids, but rather as sister taxa of crown Strepsirrhini; Afradapis and Darwinius are placed in a geographically widespread clade of caenopithecine adapiforms that left no known descendants. The specialized morphological features that these adapiforms share with anthropoids are therefore most parsimoniously interpreted as evolutionary convergences. As the largest non-anthropoid primate ever documented in Afro-Arabia, Afradapis nevertheless provides surprising new evidence for prosimian diversity in the Eocene of Africa, and raises the possibility that ecological competition between adapiforms and higher primates might have played an important role during the early evolution of stem and crown Anthropoidea in Afro-Arabia.
