Hominoid Morphology

From Primatome.com

Hominoids are distinguished from Old World Monkeys by a variety of both primitive catarrhine features and unique specializations. Like cerecopithecoids, all living hominoids have a tubulartympanic bone and a dental formula of 2.1.2.3. Compared to Old World Monkeys, hominoids have relatively primitive molar teeth, with rounded cusps rather than the bilophodont crests of monkeys. The lower molars are characterized by an expanded talonid basin surrounded by five main cusps. The upper molars are quadrate and have a distinct trigon anteriorly and a large hypocone posteriorly. The anterior lower premolar varies in shpae from an elongate shearing blade in gibbons to a bicuspid tooth in humans. Most hominoids have relatively broad incisors. Hominoid canines are much more variable than those of cercopithecoids in both shape and degree of sexual dimorphism.

Hominoids are characterized by relatively broad palates, broad nasal regions, and large brains. Hominoid skeletons show a variety of distinctive features. The axial skeletion is characterized by a reduced lumbarl region, an expanded sacrum, and the absence of a tail. All hominoids have a relatively broad thorax with a dorsally positioned scapula.

Hominoids have relativelty long upper limbs, and theirelbow joint is characterized by a spool-shaped trochlea on the humerus and a short olecranon process on the ulna. Their wrist lacks an articulation between the ulna and the carpal bones; instead, a fibrous meniscus separates the two bones. The hindlimbs of hominoids are characterized by a broad ilium, broad femoral condyles, and usually a large, robust hallux.

-from Primate Adaptation and Evolution by John G. Fleagle (Author)