The two cranio-dental characteristics that group proconsul with hominoids to the exclusion of Cercopithecoids are the Y-5 and the Wider anterior palate.
Proconsul is an extinct primate which lived approximately 23 to 17 million years ago during the Early Miocene period. It was discovered in 1909 by a gold prospector in Western Kenya, Africa. Cercopithecoids have a narrow nose and palate, and smaller brain relative to body size than Hominids. They also had tails, while Hominoids have no tails.