eo-

eo- prefix used from mid-19c. (first in EOCENE (Cf. Eocene)) in compound words formed by earth-scientists and meaning “characterized by the earliest appearance of,” from Gk. eos “dawn,” from PIE *aus-, cognate with Mod.Eng. EAST (Cf. east) (q.v.). Piltdown Man, before exposed as a fraud, was known as Eoanthropus.