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.
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.