THEROPITHECUS ATLANTICUS (THOMAS, 1884) (PRIMATES, CERCOPITHECIDAE) FROM THE LATE PLIOCENE OF AHL-AL-OUGHLAM, CASABLANCA, MOROCCO

The site of Ahl al Oughlam near Casablanca, Morocco, dated to ca. 2.5 Ma, has yielded a good sample of Theropithecus atlanticus (Thomas, 188 4), a North African late Pliocene species previously known only by its holotype, a lower molts from Algeria. Theropithecus atlanticus, which can now be much better defined, is clearly distinct from other specie s of the genus, which is thus more diverse than previously thought. Th e mandible of T. atlanticus has a very characteristic deep and long po st-molar suicus and a deep and well excavated supra-lateral triangular depression of the ramus, with a sharp postero-inferior ridge. The upp er and lower canines are rather large but low. The male P-3 is very wi de, with well developed posterior crests; the P-4 is rounded, with a l arge talonid and weak notches and clefts. Median lingual notches of th e lower molars form an acute angle. Although our incomplete knowledge of T. atlanticus precludes a detailed phylogenetic analysis, we sugges t that it arose by cladogenesis from the T. darti-T. oswaldi lineage; it is replaced by the latter species in the Pleistocene. (C) 1998 Acad emic Press Limited.