Final answer:
The first fossil monkeys occur in the Oligocene epoch (34-22 MYA), with early apes such as Proconsul appearing in the Miocene epoch (23-5 MYA). The oldest primitive primate is Purgatorius from the Paleocene epoch (65-54 MYA), and by the late Miocene, the first hominids emerged, leading to bipedalism.
Step-by-step explanation:
The Earliest Apes in the Fossil Record
The Oligocene epoch, ranging from approximately 34 MYA to about 22 MYA, is significant for the appearance of the first fossil monkeys. Early haplorrhine fossils, which include the ancestral forms of New World and Old World monkeys, were discovered in the Fayum region of Egypt.
Dating further back, the Paleocene epoch (65-54 MYA) presented us with Purgatorius, the most primitive primate yet identified, instrumental in primate evolution discussion. However, if we are specifically focusing on the earliest apes, we turn to the Miocene epoch (23-5 MYA), which contains fossil evidence of Proconsul and Sivapithecus, among others. These apes are seen as predecessors to modern apes and humans due to several physical traits such as dental patterns and facial morphology.
Aside from these, the late Miocene era (10-5 MYA) is important as it harbors the first hominid fossils, marking a crucial turning point towards bipedalism and more complex evolutionary pathways leading to modern humans.