primate - "high bishop," 12c., from M.L. primas (gen. primatis) "church primate," from L.L. primas "of the first rank, chief, principal," from primus "first" (see prime (adj.)). Meaning "biological order including monkeys and humans" is 1898, from Mod.L. Primates, from pl. of L. primas so called from supposedly being the "highest" order of mammals (originally also including bats).
'Primate' : Definition and Etymology
Planet of the Apes
Primates and the Basis of Morality
Endangered species of apes, monkeys, and lemurs