The Indo-European root *aus- ‘to shine’ gave rise not only to English east and Easter and Latin aurora, but also to Greek eos ‘dawn.’ From that comes the eo- that appears as a first element in several learned coinages, where it means ‘dawn’ in the figurative sense of ‘earliest, most primitive.’ One such coinage is eohippus, or ‘dawn horse,’ a name given to the earliest distinguishable ancestor of the modern horse. The eohippus (for which Spanish has the additional form eohipo) was originally the size of a dog; it developed in the Americas and ultimately died out there, but not before its larger descendants had colonized other continents, from which they were reintroduced into the Americas beginning at the end of the 1400s.
Another eo- word, one whose second element comes from Greek kainos ‘recent,’ is Eoceno/Eocene, which the 1911 Encyclopedia Britannica identified this way: “in geology, the name suggested by Sir C. Lyell in 1833 for the lower subdivision of the rocks of the Tertiary Era. The term was intended to convey the idea that this was the period which saw the dawn of the recent or existing forms of life, because it was estimated that among the fossils of this period only 31% (roughly a third) of the species are still living. Since Lyell’s time much has been learned about the fauna and flora of the period, and many palaeontologists doubt if any of the Eocene species are still extant, unless it be some of the lowest forms of life. Nevertheless the name is a convenient one and is in general use. The Eocene as originally defined, however, was not long left intact, for E. Beyrich in 1854 proposed the term ‘Oligocene’ for the upper portion, and later, in 1874, K. Schimper suggested ‘Paleocene’ as a separate appellation for the lower portion. The Oligocene division has been generally accepted as a distinct period, but ‘Paleocene’ is not so widely used.”
Today’s dictionaries show Eoceno/Eocene referring to ‘the second epoch of the Tertiary Period.’ (It’s as if scientists instituted something akin to a permanent Daylight Saving Time for the Eocene, bumping it up one level.)
Users of Canon single-lens reflex (SLR) digital cameras may wonder if EOS, the designation for those models, was taken from Greek eos, but the name arose as an English-language acronym for ‘Electro-Optical System.’ As a recent afterthought, however, Canon took advantage of the Greek word’s meaning and reinterpreted EOS as ‘Goddess of the Dawn’ in its online Canon Camera Museum.
© 2015 Steven Schwartzman