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 Darwinius6, 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.
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We thank K. C. Beard, P. Chatrath, B. Engesser, M. Hellmund, J. Galkin, P. D. Gingerich, M. Godinot, G. Gunnell, E. Ladier, B. Marandat, L. Marivaux, K. D. Rose, I. Rutzky and P. Tassy for access to adapiform fossils and casts. F. Ankel-Simons and J. Fleagle provided comments on the manuscript. Collaborative palaeontological research in Egypt is made possible through cooperation with the Egyptian Mineral Resources Authority and the Egyptian Geological Museum. Fieldwork in Egypt is managed by P. Chatrath. This research has been funded by the Research Foundation of SUNY, and grants from the US National Science Foundation and The Leakey Foundation to E.R.S. and E.L.S. This is Duke Lemur Center publication 1155.
Author Contributions E.R.S. and E.L.S. recovered the fossils of Afradapis along with other members of their field crews in Egypt; E.R.S. assembled the character matrix and all figures, created Figs 2 and 3, ran the phylogenetic analyses, and compiled the Supplementary Information document; E.R.S. and J.M.G.P. analysed the fossils and wrote the manuscript; D.M.B. and J.M.G.P. CT-scanned fossils and provided three-dimensional reconstructions for Fig. 1. D.M.B. scored plesiadapiforms in the character matrix and helped to write the manuscript. E.L.S. helped to write the manuscript.
This file contains dental measurements of Afradapis longicristatus gen. et sp. nov., full results of phylogenetic analyses, morphological character support for nodes within Strepsirrhini, the morphological character matrix, and the constraint tree used in the phylogenetic analysis.