Wildlife of Sierra Leone
Sierra Leone has 15 identified species of primates that include bushbaby, monkeys and a great ape, the common chimpanzee which is Sierra Leone's largest primate. Chimpanzees are found across the country with the 2010 chimpanzee census estimated a wild population in excess of 5500 more than double the number previously thought to live in the country. This is the second largest population of the endangered subspecies of western chimpanzee, after Guinea,
with the largest density in the Loma area, 2.69 individuals per km2, and the Outamba, with 1.21 individuals per km2.
List of fossil primates
The order Primates, established by Linnaeus in 1758, includes humans and their immediate ancestors. However, contrarily to the common opinion, most primates do not have especially large brains. Brain size is a derived character, which only appeared with genus "Homo", and was lacking in the first hominid. In fact, hominid encephalization quotient is only 1.5 Ma more recent than that of some dolphin species. The encephalization quotient of some cetaceans is therefore higher than that of most primates, including the nearest relatives of humans, such as "Australopithecus".