Final answer:
During the Miocene epoch, the significant evolutionary development was the rise of early apes, including the likes of Proconsul and Sivapithecus, along with diversification of other mammal families. This period laid the groundwork for primate evolution, the appearance of the first hominids, and eventually, the rise of bipedal hominins.
Step-by-step explanation:
The evolutionary development that took off during the Miocene epoch was the emergence and diversification of the earliest apes, including species like Proconsul africanus and Sivapithecus. This period spans from approximately 23 million to 5 million years ago. The Miocene saw significant primate evolution, where various species adapted to different ecological niches, leading to the appearance of many traits found in modern primates. The Proconsul lacked long, curved digits and a tail, indicating that they moved about on all four limbs, while Sivapithecus demonstrated dental and cranial resemblances to modern orangutans. Furthermore, the Miocene epoch was a time of considerable mammalian diversification in general, including the development of various other modern mammal families, the evolution of horses, and the appearance of mastodons.
By the end of the Miocene, the first hominids began to appear, indicating an evolutionary shift towards hominids that would eventually lead to the rise of humans. While hominids first appear in the late Miocene, it was during the subsequent Pliocene epoch when evidence of hominins displaying clear bipedalism and primitive cultural behavior became more prevalent.