Eastern gorilla
There are two recognised subspecies of eastern gorilla: the mountain gorilla ("Gorilla beringei beringei") of the volcanic slopes of Rwanda, Uganda and eastern Democratic Republic of Congo; and Grauer's gorilla or eastern lowland gorilla ("Gorilla beringei graueri") in eastern Democratic Republic of Congo.
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.