Final answer:
The first anthropoids appeared in the Eocene epoch, over 55 million years ago, during the Cenozoic era. They resemble early prosimians and are ancestors to monkeys, apes, and humans.
Step-by-step explanation:
The first anthropoids, ancestral to monkeys, apes, and humans, appeared more than 55 million years ago. This period corresponds to the Eocene epoch of the Cenozoic era. During this time, early primates that resembled present-day prosimians such as lemurs were found in various regions including North America, Europe, Asia, and Africa. As evolution progressed, these early primates started to exhibit characteristics that would lay the foundation for the development of later monkeys, apes, and eventually, hominids. It's important to understand the geological timescale when considering the evolution of primates, the epochs that categorize significant stages in their development, and the eras that contextualize these changes on a broader scale.