Eastern gorilla
The eastern gorilla ("Gorilla beringei") is a critically endangered species of the genus "Gorilla" and the largest living primate. At present, the species is subdivided into two subspecies. Grauer's gorilla, formerly known as the eastern lowland gorilla ("G. b. graueri") is more populous, at about 3,800 individuals. The mountain gorilla ("G. b. beringei") has only about 1000 individuals. The International Union for the Conservation of Nature mentioned illegal hunting in its assessment of threats to the species.
Prosimian
While primates are often thought of as fairly intelligent animals, the prosimians are not very large-brained compared to other placental mammals. Their brain-cases are markedly smaller than those of simians of comparable sizes. In the large-eyed tarsiers, the weight of the brain is about the same as that of a single eye. Prosimians generally show lower cognitive ability and live in simpler social settings than the simians. The prosimians with the most complex social systems are the diurnal lemurs, which may live in social groups of 20 individuals. The nocturnal prosimians are mainly solitary.