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.
Biretia
The smallest of the species, "B. fayumensis", had an estimated weight of 273 g, while the largest, "B. megalopsis", had a weight of about 376g. Adaptations of the skull of "B. megalopsis" are easily comparable to the modern tarsiers, a small, modern Asian primate with a nocturnal insectivorous lifestyle. We can infer the possibility of a nocturnal lifestyle for "B. megalopsis"' from the animal's molar roots, which are truncated to accommodate for large eye sockets typical of a nocturnal primate. The large eye structure and similarity to the modern tarsiers also suggests that it has lost its tapetum lucidum. Thus, "B. megalopsis" demonstrates itself as being the oldest known nocturnal primate.