Mammals

The process of carrying young inside the body from fertilization to birth. Gestation is the time when a baby develops inside the mother's womb.

A primate that walks upright, has a large brain, opposable thumbs, and no tail. Hominid. A hominid is a type of primate that includes humans and their fossil ancestors.

Primates that can walk on two legs, like orangutans, gorillas, chimpanzees, and humans. Hominoids are a group of primates that include all apes and humans, characterized by their lack of tails and ability to walk upright.

Extinct mammal-like reptiles that evolved into mammals. Therapsid. Therapsids are ancient reptiles that served as ancestors to modern mammals.