Henry Fairfield Osborn, “Hunting the ancestral elephant in the Fayûm desert”:
One of the most fascinating problems of paleontology, therefore, is to ascertain the birthplace of each of the great animal groups -- the fertile or arid nursery wherein they first took on their peculiar and characteristic form, and, like the races of man, felt the power and strength to go forth and invade the lands of other races.
Osborn HF. 1907. Hunting the ancestral elephant in the Fayûm desert: Discoveries of the recent African expedition of the American Museum of Natural History. The Century Magazine 74(6):815-835.