New adapiform primate fossils from the late Eocene of Egypt

Abstract

Caenopithecine adapiform primates are currently represented by two genera from the late Eocene of Egypt (Afradapis and Aframonius) and one from the middle Eocene of Switzerland (Caenopithecus). All are somewhat anthropoid-like in several aspects of their dental and gnathic morphology, and are inferred to have been highly folivorous. Here we describe a new caenopithecine genus and species, Masradapis tahai, from the ~37 million-year-old Locality BQ-2 in Egypt, that is represented by mandibular and maxillary fragments and isolated teeth. Masradapis is approximately the same size as Aframonius but differs in having a more dramatic distal increase in molar size, more complex upper molar shearing crests, and an exceptionally deep mandibular corpus. We also describe additional mandibles and part of the orbit and rostrum of Aframonius which suggest that it was probably diurnal. Phylogenetic analyses place Masradapis either as the sister taxon of Aframonius (parsimony), or as the sister taxon of Afradapis and Caenopithecus (Bayesian methods). Bayesian tip-dating analysis, when combined with Bayesian biogeographic analysis, suggests that a common ancestor of known caenopithecines dispersed to Afro-Arabia from Europe between 49.4 and 47.4 Ma, and that a trans-Tethyan back-dispersal explains Caenopithecus’ later presence in Europe.

For Masradapis: https://www.zoobank.org/urn:lsid:zoobank.org:act:41BC8459-7CCE-487F-BC59-1C34257D5C4E

For Masradapis tahai: https://www.zoobank.org/urn:lsid:zoobank.org:act:C0A620AD-6FCA-4649-A980-FCA237AFE39D

Keywords:

• Eocene
• Oligocene
• Africa
• Strepsirrhini
• primates
• phylogeny

View correction statement:

Corrigendum

Acknowledgements

We are grateful for the opportunity to contribute to this volume in honour of Percy Butler, and acknowledge the profound impact that his research has had on our understanding of mammalian evolution and particularly the evolution of the mammalian dentition. The palaeontological work that led to the recovery of the specimens described here was led by the late Elwyn L. Simons and managed by Prithijit Chatrath, both of Duke University, and undertaken in collaboration with the Egyptian Geological Museum and the Egyptian Environmental Affairs Agency, and we gratefully acknowledge them and our Egyptian colleagues (particularly Medhat Adbel-Ghany, Afifi Hassen, and the late Yousry Attia, all of the CGM, and Gebely Abuelkheir of the EEAA) for the roles they played in facilitating this research. Judit Marigó (Institut Català de Paleontologia Miquel Crusafont) provided comments and suggestions that improved the manuscript. Steven Heritage assisted with micro-CT scanning at Stony Brook University. We also thank the many field crews who have helped to excavate the BQ-2 locality since 2001, and particularly Mark Mathison (Iowa State University). This is Duke Lemur Center publication #1344.