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. The functional length of the femur is estimated to be 150 mm, which is larger than Cebus apella and smaller than Alouatta seniculus. Brain size In Egypt’s Fayum Depression a subadult female cranium, CGM 85785, was discovered by Rajeev Patnaik. This specimen’s cranial capacity was found to be 14.63 cm3 and reanalysis of a male endocast (CGM 40237) estimates a cranial capacity of 21.8 cm3. These estimates dispel earlier ones of approximately 30 cm3. These measurements give an estimated male to female endocranial ratio of approximately 1.5, indicating A. zeuxis to be a dimorphic species. The olfactory bulb to endocranial volume ratio is considered to be on the lower end of the strepsirrhine spectrum, perhaps as a result of the organism’s rostrum. In relation to other anthropoids, the frontal lobes of A. zeuxis are considered to be rather small but the olfactory bulbs are not considered to be small when taking into account the body size of A. zeuxis. Overall, the brain to body weight ratio of A. zeuxis is considered to be strepsirrhine-like and perhaps even non-primate like. Behaviour Aegyptopitheccus zeuxis is thought to have been sexually dimorphic. Tooth size, craniofacial morphology, brain size, and body mass all indicate this. Due to A. zeuxis being sexually dimorphic, the social structure is thought to have been polygynous with intense competition for females. Locomotion Three femoral remains were found in Quarry I (DPC 5262 and 8709) and Quarry M (DPC 2480). Paleomagnetic dating puts the sites at 33 Ma, consistent with the Oligocene epoch. Based on estimated femoral neck angle (120-130 degrees) of aforementioned remains, the femur is similar to that of a quadrupedal anthropoid. The greater