During which epoch did the first primates appear?

The first primates appeared during the Eocene epoch, which lasted from about 56 to 33.9 million years ago. This period is significant in the evolutionary history of primates because it is when the earliest forms of true primates, known as euprimates, began to emerge. Fossil evidence from this epoch shows a diverse range of primate species that had adaptations suitable for a tree-dwelling lifestyle, such as grasping hands and feet, stereoscopic vision, and larger brains relative to body size.

The Paleolithic epoch, primarily associated with early human stone tool usage, and the Miocene epoch, known for the rise of many modern mammal species and the diversification of apes, occurred later than the Eocene and do not represent the period when primates first appeared. The Cretaceous period is notable for the dominance of dinosaurs, with mammals being relatively small and insignificant during that time, making it an unlikely period for the emergence of primates. Thus, the Eocene stands out as the epoch in which the first true primates made their appearance in the fossil record, establishing a foundation for the primate lineage.