The lacrimal fossa of cercopithecoidea, with special reference to cladistic analysis of Old World monkey relationships

Re-examination of lacrimal fossa patterns in extant cercopithecoids indicates that the last common ancestor of Cercopithecini and Papionini, and hence of Cercopithecinae, probably retained a maxillary contribution to the lacrimal fossa, as did the common ancestor of Colobinae. Consequently, the presence of a maxilla-lacrimal fossa cannot be used to assess the subfamily affinity of Old World monkeys. In addition to being correlated with general facial lengthening, the derived, exclusively lacrimal pattern of Erythrocebus, Mandrillus, Papio, Theropithecus and some (but not all) guenons, macaques and mangabeys may be associated with extreme narrowing of the interorbital septum. Moreover, the derived condition may have evolved in response to independent exploitation of open country habitats as it enhances protection of the lacrimal sac and serves to reduce eye infection in terrestrial species.