Primate Origin

tributes to heated debates about their phylogenetic relationships. There are as many
morphological similarities between fossil and extant cercopithecines as there are morphological
differences between fossil and living colobines. Therefore, given that we
cannot resolve evolutionary relationships between these basal monkeys, a complete
review of the phylogenetic relationships to extant monkeys is best left for more advanced
work and study. Despite these issues, there is no valid scientific reason to invoke
either intelligent design or creationism as alternatives to evolution when
reviewing Pliocene monkeys (Figure 5.15). As more fossil primates are recovered and
new phylogenetic techniques are employed, researchers will be better prepared to resolve
phylogenetic relationships in Pliocene monkeys.
Summary
1. Fossil primates are represented largely by dental remains; cranial and postcranial materials
are rarely found. Thus, most research on primate origins involves detailed analysis of teeth.
2. General patterns of diet, locomotion, activity patterns, and even social organization can be
learned from careful studies of fossil primates. Specifically, paleoanthropologists use the
comparative method to understand morphological adaptations in fossil primates.
3. There are three main hypotheses on primate origins: the arboreal theory, the visual predation
theory, and the angiosperm co-evolution theory.
4. The earliest mammals somehow survived a massive global extinction event about 65 million
years ago. It is possible that the first primates evolved before or during the Paleocene,
although the first definitive primates show up in the Eocene. Oligocene primates exhibit
broad morphological similarities to some modern monkeys. The Miocene witnessed an explosive
radiation of ape-like primates, which slowly disappeared during the Pliocene.
Figure 5.14
Side view of skull
from Theropithecus
oswaldi.
This was a giant, extinct
cercopithecine that lived
during the Pliocene.
© K. Folinsbee