Final answer:
The emergence of primates in the Eocene epoch was marked by the presence of postorbital bars composed entirely of bone, a toothcomb and/or grooming claw, and specific ankle bone characteristics. These developments shaped the evolution and success of primates during this period.
Step-by-step explanation:
The emergence of primates in the Eocene epoch (56-34 million years ago) was marked by several key developments and characteristics. One important characteristic is the presence of postorbital bars composed entirely of bone, which surround the eye sockets. This is a distinct feature of primates compared to other mammals whose postorbital bars are part bone and part cartilage. Another characteristic is the presence of a toothcomb and/or grooming claw, which are found exclusively in strepsirrhine primates today. Additionally, researchers believe that the evolutionary success of primates during this period was influenced by anatomical characteristics such as the shape of the ankle bones.