Neogene

During the Neogene, the world continued to cool from the warm climates of the earlier Cenozoic, with the formation of ice sheets in Antarctica and, later in the period, in the Northern Hemisphere. The cooling trend caused the spread of grasslands, which led to a diversification of grazing animals such as horses, camels, and antelope. Predators, including large felids and canids, also evolved to adapt to these open environments.

The Miocene epoch (23 – 5.3 million years ago) saw a peak in mammalian diversity. Forests began to shrink as grasslands expanded, resulting in significant evolutionary adaptations among herbivores and carnivores. Early apes (Hominoidea) also flourished during the Miocene, with many species radiating across Africa, Europe, and Asia. Fossil evidence from the Miocene provides insights into the evolutionary pathways leading to modern primates and, eventually, humans.

The Pliocene epoch (5.3 – 2.58 million years ago) continued the trend of global cooling and saw further ecological transformations. The closure of the Central American Seaway, due to the joining of North and South America, played a major role in altering ocean currents and climate patterns. This tectonic shift led to changes in global climate, such as the intensification of the North Atlantic Conveyor, which contributed to the development of Northern Hemisphere glaciation.

The Pliocene is also significant for the evolution of early hominins, including Australopithecus and Ardipithecus, key ancestors of modern humans. These early hominins were bipedal and adapted to both forested and savannah environments in Africa, marking a major step in human evolution.