The purpose of this application, under Articles 23.9.3 and 81.1 of the Code, is to conserve the usage of the species-group name Simopithecus oswaldi by giving it precedence over its senior subjective synonym Cynocephalus atlanticus . Theropithecus is a common to dominant member of the extinct primate community across Africa after 4 million years ago () and often co-occurred with extinct humans (Hominini); fossils are also known rarely across Eurasia (Roberts et al., 2014). Most fossil samples are currently included in Theropithecus oswaldi (), which is often divided into chrono-geographic subspecies. Cynocephalus atlanticus was not recognized as a member of Theropithecus until 1973, and this nomen has seldom been used, but if it were shown (as seems likely) to be conspecific with Simopithecus oswaldi , widespread paleontological usage would be upset. It is thus proposed to give conditional precedence to the later name, which would still permit the use of Theropithecus atlanticus as a distinct species or subspecies of Theropithecus oswaldi. Lectotypes are designated for Simopithecus oswaldi olduvaiensis and Simopithecus oswaldi hopefieldensis .