Final answer:
The earliest known primate is Purgatorius from the Paleocene epoch, identifiable by its unique dental features. It lived in modern-day Montana and shared traits with other archontans. Primatology reveals our close genetic and evolutionary links to other primates, marked by significant milestones in primate evolution.
Step-by-step explanation:
The earliest primate yet discovered is called Purgatorius, which lived during the Paleocene epoch that began approximately 65 million years ago (MYA) and ended about 54 MYA. Purgatorius is known for having an elongated last lower molar and an enlarged upper central incisor, characteristics seen in modern primates. Though not much is known about its diet, it likely consumed a range of foods similar to other small mammals of its time. This creature lived in what is now the U.S. state of Montana. Purgatorius shared some of its morphological traits with other archontans, a group that includes primates, but its distinct primate-like trait was the dental characteristics mentioned above, which have been maintained in all living primates.
When we consider the evolution of primates, the first true primates appeared in the Eocene epoch, about 55 MYA, followed by later diversification into groups like the Miocene apes such as Proconsul and Sivapithecus. The primates of the Oligocene epoch, marking the appearance of the first fossil monkeys, show further evolution with distinctive dental formulas and limb adaptations.
Furthermore, as humans, we share a significant amount of our DNA with other primates, highlighting the close evolutionary relationship we have within this diverse group of mammals. Primatology helps us understand not only our ancestry but also the diversity and adaptation of primates through time.