Final answer:
The Eocene epoch marked the evolution of early primates, like Notharctus, with anatomical features such as a fully bony postorbital bar, indicative of the significant evolutionary advancements during this period. Fossils demonstrate a wide distribution across continents, but none in South America or Antarctica.
Step-by-step explanation:
The Eocene epoch, a significant period in primate evolution, marks the first appearance of primates more similar to modern strepsirrhine primates. Notably, the Notharctus, which is part of the Notharctids, represents one of these primates from the Eocene epoch.
These early primates are characterized by distinct anatomical features such as a postorbital bar made entirely of bone, in contrast to the partial bone and cartilage composition seen in other mammals.
This feature, along with the development of ankle bones, toothcombs, and grooming claws, underscores the significant evolutionary advancements during this time.
The Eocene also saw a proliferation of strepsirrhine primates, with fossil evidence suggesting there were four times as many of these primates then as there are living primates today.
Fossil records from North America, Europe, Asia, and Africa provide insight into the diversity and spread of Eocene primates, although no such fossils have been found in South America or Antarctica.