word-forming element, used from mid-19c. (first in Eocene) in compound words formed by earth-scientists, and meaning "characterized by the earliest appearance of," from Greek ēōs "dawn, morning, daybreak," also the name of the goddess of the morning, from PIE root *aus- (1) "to shine," especially of the dawn. Piltdown Man, before exposed as a fraud, was known as Eoanthropus.
"pertaining to the later Stone Age, belonging to the period of highly finished and polished stone implements," 1865, coined by John Lubbock, later Baron Avebury, (1834-1913) from neo- "new" + -lith "stone" + -ic.
<a href="https://www.etymonline.com/word/eolithic">Etymology of eolithic by etymonline</a>
Harper, D. (n.d.). Etymology of eolithic. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/eolithic