"stone presenting a fossil footprint," 1841, from Latinized form of Greek ikhnos "a track, footprint" (which is of unknown origin) + -lite. Ichnite in the same sense is from 1854. Ichnology, "scientific study of fossil footprints," is from 1837.
So numerous have been the discoveries of fossil footmarks in Europe within a few years past, and so many species occur in this country, that it will be at least convenient to have them designated by some appropriate scientific terms, and to arrange them in systematic order. I propose the term Ichnolite ... to include them all and to be the name of the Class. [Edward Hitchcock, LL.D., "Final Report on the Geology of Massachusetts," 1841]