Final answer:
The Cenozoic era is the geological time frame in which primates evolved, with early primate fossil evidence like Purgatorius showing key characteristics of primates. Primate evolution unfolded throughout the epochs of the Cenozoic, with significant developments during the Eocene, Oligocene, and Miocene epochs.
Step-by-step explanation:
Early Primate Evolution in the Cenozoic Era
The Cenozoic era also referred to as the age of mammals, spans from about 65 million years ago to the present day. It was during this era that primates, including the prosimians, monkeys, and apes, evolved. The early primate known as Purgatorius, identified from fossil evidence in Montana, displays key primate characteristics such as an elongated last lower molar and an enlarged upper central incisor, suggesting it might be a common ancestor to later primates.
Phases of Primate Evolution
Primate evolution in the Cenozoic era went through several phases, starting with the primitive forms in the Paleocene epoch. It continued with the emergence of true primates by the Eocene epoch, around 55 MYA. These early primates had similarities with current prosimians. As time progressed, the Oligocene epoch witnessed the first fossils of monkeys, and by the Miocene, we see evidence of early apes like Proconsul and Sivapithecus, showcasing a pattern of tooth configuration (2.1.2.3) akin to that of Old World monkeys and apes, including humans. The various epochs of the Cenozoic era, such as the Eocene, Oligocene, and Miocene, were pivotal in the diverse evolutionary paths that led to the primate species we know today.