Scapula of Apidium phiomense: a small anthropoid from the Oligocene of Egypt

Abstract

A scapular fragment from the Upper Fossil Wood Zone, Quarry I, Fayum Depression, Egypt, is assigned to the taxon Apidium phiomense. This animal may have approximated the size of Galago crassicaudatus or Nycticebus coucang, as predicted by regressing body weight on glenoid surface area and fossa length for an assortment of living primates. Morphometric values for spinoglenoid, axilloglenoid, and axillospinal angles indicate locomotor affinities of A. phiomense with colobine monkeys. Other nonmetric traits align the fossil with Saimiri sciureus, probably its closest behavioral analogue. A. phiomense is thus characterized as an arboreal quadruped with a locomotor repertoire that includes a considerable amount of leaping and the use of forelimbs for clinging and/or suspending during landing.