Another name used to describe the first primate-like mammals that were evolving by the beginning of the Cenozoic Era 65 million years ago. They were roughly similar to squirrels and tree shrews in size and appearance. The existing, very fragmentary fossil evidence suggests that they were adapted to an arboreal way of life in warm, moist climates.

Latin terms used to refer to the plants and animals in an environment.

The biological order of mammals that was named for their adaptation to eating insects. They were among the earliest of the placental mammals to evolve. They first appeared before the end of the Mesozoic Era.

The relatively rapid expansion and diversification of an evolving group of organisms as they adapt to new ecological niches. This is the process by which one species evolves into two or more species. This occurs as a result of different populations becoming reproductively isolated from each other, usually by adapting to different environments.

The geologic epoch that occurred about 55.8-33.9 million years ago. It was during this epoch that early forms of most of the placental mammal orders that are present today first appeared. Among them were primate species that somewhat resemble modern prosimians such as lemurs, lorises, and possibly tarsiers. This was the epoch of maximum prosimian adaptive radiation.

The term for the hole at the base of a skull through which the spinal cord passes. It literally means a "large hole or opening" in Latin.

The 1200 mile long depression or valley system running northeast to southwest in East Africa. This valley system with lakes and grasslands developed in a volcanically active fault zone at the juncture of two large tectonic plates.

The geological epoch that occurred about 33.9-23 million years ago. It was in this epoch that the first monkeys evolved from prosimians. By the beginning of this epoch, North America and Europe drifted apart and became distinct continents. The Great Rift Valley system of East Africa also was formed. The Himalayan chain of mountains and the Tibetan Plateau beyond rose high as the Indian tectonic plate continued to crash into Asia. This epoch follows the Eocene Epoch.

The general term for a seasonally dry tropical or subtropical grassy plains with scattered trees. These environments are usually the habitat of large herbivores and their predators. The first hominids apparently evolved on and near East and South African areas like this.

The geological epoch that occurred about 23-5.3 million years ago. It was during this epoch that apes evolved from monkeys. Fossil monkeys and prosimians are comparatively rare from most of this epoch, but apes are common. By 14 million years ago, the group of apes that included the ancestors of humans were apparently in the process of adapting to life on the edges of the expanding savannas in Southern Europe.

The term for a four-footed form of locomotion. This is characteristic of most mammals. Humans are exceptions, being bipeds.