Last of the oligopithecids? A dwarf species from the youngest primate-bearing level of the Jebel Qatrani Formation, northern Egypt

摘要

Oligopithecids are basal stem catarrhines that make their first definitive appearance in the fossil record in the latest Eocene of Egypt. Previously, the group was assumed to have gone locally extinct in northern Africa shortly after the Eocene-Oligocene boundary, with a last record at the ~31.5 Ma Taqah locality in Oman. Here we describe a tiny oligopithecid from the youngest (~29.5-30 Ma) primate-bearing horizon in the Jebel Qatrani Formation, based on a partial hemimandible with a largely complete first molar. This is the first record of an oligopithecid in the upper sequence of that Formation, occurring ~160 m above the next-youngest oligopithecid-bearing locality (Quarry E), and provides a new last appearance datum for Oligopithecidae. The species is markedly smaller than its older oligopithecid relatives Catopithecus and Oligopithecus, and indeed is one of the smallest anthropoids known, suggesting that it represents a member of a dwarfed lineage. This material adds to the evidence provided by the co-occurring species Afrotarsius chatrathi and Qatrania fleaglei for a fairly diverse, but exceedingly rare, small primate fauna at a horizon that is otherwise dominated by much larger and more derived propliopithecids and parapithecids.