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.
Mammal
The earliest known ancestor of primates is "Archicebus achilles" from around 55 million years ago. This tiny primate weighed 20–30 grams (0.7–1.1 ounce) and could fit within a human palm.