The ancestors of catarrhine primates, the Old World
monkeys, apes, and humans, evolved about 35 million years ago.
Parapithecus and Apidium were fruit eating primates with a 2-1-3-3 tooth
pattern of prosimians and New World monkeys. They may be close to the
ancestral stock of both groups of anthropoids. Unlike New World monkeys,
however, they had 5 cusps on lower molars (Simons, 1995).
Oligopithecus savagei lived 35 million years ago. It possessed some prosimian
characteristics in its teeth but it was the earliest primate to have the
2-1-2-3 tooth pattern that distinguishes the cusps on lower molars as
in catarrhines (Delson, 1975).
Propliopithecus had the 2-1-2-3 tooth pattern but its incisors did not
project forward as in modern catarrhines. Its premolars were not one-cusped
as in apes and its skeleton suggests a leaping lifestyle. Some species
may have given rise to Aegyptopithecus. Some feel that Propliopithecus
also gave rise to Old World monkeys. Several species are recognized including
P. haekeli, P. markgrafi, P. ankeli, and P. chirobates (Simons, 1995;
Aegyptopithecus zeuxis lived 34-33 million years ago and is considered
to be ancestral to both Old World monkeys and apes. It had dental &
facial similarities to the later apes Proconsul and Dryopithecus but still
maintains some prosimian aspects of the skull not found in any hominoids.
Its teeth and jaws were apelike yet it had a tail as in monkeys. There
was a large sagittal crest on the top of the skull. It weighed 9-10 pounds,
similar to the size of a gibbon. Its limb proportions suggest it lived
in the trees. From its brain endocast, it had a small brain but an enlarged
visual cortex (Simons, 1995)..