Primate Origin

What do we know about these monkeys? The earliest platyrrhines were small
monkeys weighing about 500 to 1000 g. Although they have the characteristic platyrrhine
dental formula of 2.1.3.3., the low, rounded cusps on their teeth are similar to
those seen in some primate fossils from the late Eocene in the Fayum region of Egypt.
Paleoanthropologists conclude that these early fossil platyrrhines were frugivores. Few
cranial and no postcranial remains have been recovered, which limits any theories on
the activity and locomotor patterns of fossil platyrrhines from the Oligocene.
Phylogenetic Relationships among Oligocene Primates
Phylogenetic analysis of Oligocene primates has resulted in more debate than consensus
on their evolutionary relationships. Because the remains are fragmentary and the
vast majority of Oligocene fossils come from only a few sites in Africa and South
America, a conservative approach is needed to summarize their phylogenetic relationships.
What we can say here is that there is general support for the parapithecids being
ancestral to a clade forming the propliopithecids and the fossil platyrrhines (Figure
5.11). Put differently, propliopithecids share a more recent common ancestor with
each other than either does with the parapithecids. As with earlier epochs, we desperately
need students like you to unearth Oligocene primates from new sites. Only with
these additional specimens will paleoanthropologists be able to start sifting through
the bewildering array of hypotheses on evolutionary relationships among fossil lemurs,
Old World monkeys, and New World monkeys.
Figure 5.11
Phylogenetic relationships
of Oligocene
primates.