Aegyptopithecus ("Egyptian ape", from Greek Αίγυπτος "Egypt" and πίθηκος "ape") is an early fossil catarrhine that predates the divergence between hominoids (apes) and cercopithecids (Old World monkeys). It is known from a single species, Aegyptopithecus zeuxis, which lived around 38-29.5 million years ago in the early part of the Oligocene epoch. It likely resembled modern-day New World monkeys, and was about the same size as a modern howler monkey, which is about long. Aegyptopithecus fossils have been found in the Jebel Qatrani Formation of modern-day Egypt. Aegyptopithecus is believed to be a stem-catarrhine, a crucial link between Eocene and Miocene fossils.
Discovery, age and taxonomy
thumb|Aegyptopithecus skull|left
Aegyptopithecus was discovered by Elwyn Simons in 1966 in the Gabal Qatrani Formation, located in the Faiyum Governorate of central Egypt. Its scientific name means "linking Egyptian ape".
There is controversy over whether or not Aegyptopithecus should be a genus on its own or whether it should be moved into the genus Propliopithecus.
Morphology
left|thumb|Male and female skulls ([[American Museum of Natural History|AMNH 129172/3/4/5) of A. zeuxis]]
Aegyptopithecus zeuxis was a species that had a dental formula of , with the lower molars increasing in size posteriorly. The molars showed an adaptation called compartmentalizing shear, which is where the cutting edges involved in the buccal phase serve to surround basins in such a way that food is cut into fragments that are trapped and then ground during the lingual phase.
The canines of this species were sexually dimorphic. The ascending mandibular ramus of this species is relatively broad. The orbits are dorsally oriented and relatively small which suggested that this was a diurnal species. This species showed some postorbital constriction. The interorbital distance of Aegyptopithecus zeuxis is large much like that found in colobines. A sagittal crest developed in older individuals and extends over the brow ridges. This species had an auditory region which is similar to that found in platyrrhines, having no bony tube and the tympanic fused to the lateral surface of the bulla.
The humerus has a head which faces posteriorly and is narrower than primates that practice suspensory behavior. The humerus also shares some features with extinct hominoids: a large medial epicondyle and a comparatively wide trochlea. This species had an ulna that compares to the extinct members of the genus Alouatta. On the foot bones, this species had a grasping hallux. Aegyptopithecus zeuxis shares characteristics with haplorrhines such as a fused mandibular and frontal symphyses, postorbital closure, and superior and inferior transverse tori.
Based on dental dimensions and femoral remains the body mass of A. zeuxis is estimated to be 6.708 kg. This specimen's cranial capacity was found to be 14.63 cm<sup>3</sup> and reanalysis of a male endocast (CGM 40237) estimates a cranial capacity of 21.8 cm<sup>3</sup>. In addition, the ulna and distal articular surface of the humerus indicate that A. zeuxis was not only an arboreal quadruped, but also large and slow. However, the rate of tooth chipping in Aegyptopithecus was very low, and this line of evidence indicates that it seldom consumed hard objects.
Habitat
Aegyptopithecus lived in the Fayum area of northern Egypt. Today, this area is semiarid and lacking in vegetation.