El. Simons et Dt. Rasmussen, A REMARKABLE CRANIUM OF PLESIOPITHECUS-TERAS (PRIMATES, PROSIMII) FROM THE EOCENE OF EGYPT, Proceedings of the National Academy of Sciences of the United Statesof America, 91(21), 1994, pp. 9946-9950
Between 1991 and 1993 specimens of a highly distinctive primate, named
Plesiopithecus teras [Simons, E. L. (1992) Proc. Natl. Acad. Sci. USA
89, 10743-10747], were found at site L-41 in late Eocene deposits of
the Fayum Depression, Egypt. The most important of these specimens con
sists of a nearly complete skull, which facilitates the evaluation of
affinities of this primate. Characteristics of the known material now
demonstrate that Plesiopithecus is a prosimian, although mandibular mo
lar morphology, in particular, bears similarity to that in molars of a
rchaic members of Anthropoidea. Plesiopithecus has a postorbital bar b
ut lacks posterbital closure, it has upper molars without hypocones, a
nd it may retain four lower premolars. Its familial rank was considere
d incertae sedis by Simons [Simons, E. L. (1992) Proc. Natl. Acad. Sci
. USA 89, 10743-10747]; it can now be demonstrated that Plesiopithecus
justifies establishment of a new family and superfamily. The new supe
rfamily apparently lies closer to the toothcomb prosimians (strepsirhi
nes) than to any other known primate group. Under this interpretation
the enlarged, procumbent tooth in the jaw of Plesiopithecus is homolog
ous to either the lateral incisor or the canine of the prosimian tooth
comb.