An order of the mammals (class Mammalia). These include lemurs, monkeys, apes, and humans. One distinguishing feature of primates is finger nails. Opposing thumbs is a feature too, but not unique to primates (racoons have opposing thumbs)(zoologist please confirm) Some apes have opposing thumbs on their hind legs, but not their hands. I'm not sure about monkeys and lemurs. I don't think this can be taken as a general feature of the order.
- Suborder Strepsirhini
- Suborder Haplorhini