The generic classification of Fayum anthropoidea

Abstract

The early anthropoid species initially described asAegyptopithecus zeuxis Simons, 1965, from the Oligocene of Egypt, although retained by many authors in the monotypic genusAegyptopithecus, has been lumped by others into the genusPropliopithecus. Similarly, the species originally described asParapithecus grangeri Simons, 1974, has been ranked by some authors in a monotypic genusSimonsius, while others retain it inParapithecus. Criteria to be considered in resolving these taxonomic debates are (1) the adequacy and consistency of proposed morphological differences between species; (2) analogy with the degree of morphological variation tolerated within extant genera; and (3) nomenclatural conservatism. A philosophy that would require strict monophyletic classification is of insufficient practical value for assessing the validity of Fayum genera. Characters cited as distinguishing vetweenAegyptopithecus andPropliopithecus, and betweenSimonsius andParapithecus, are reviewed and evaluated. The results indicate thatA. zeuxis is generically distinct from species ofPropliopithecus, based on differences in the crown structure and proportions of the molars.Pa. grangeri cannot be shown to differ at the generic level from the type and only known specimen ofPa. fraasi, thus establishing Simonsius as a junior synonym ofParapithecus.