The deciphering of the genealogy of the horse demonstrating Darwin's theory of evolution was the brilliant work of Othniel C. Marsh of Yale that established his reputation not only in vertebrate paleontology but in the entire scientific world. Without the pioneer efforts of Thomas Condon, first State Geologist of Oregon, however, Marsh could not have accomplished this coup in his frenzied race with his arch rival, Edward D. Cope, for scientific priority and the amassing of fossil bones.
Condon discovered in the John Day country of Oregon many specimens of new species that provided Marsh with invaluable links in the evolutionary progression. Marsh refused to return specimens which Condon loaned to him in 1871. The fossils were finally returned to Oregon in 1906, years after Marsh's death; although now mostly scattered or lost, they were discovered to include at least one specimen of Miohippus, an important link in horse evolution. Miohippus was a genus unknown before Marsh described it in his 1874 article in which he announced that he had identified the direct line of descent of the horse. Marsh never credited Condon with this discovery. The Condon story is perhaps a demonstration of the plight of the lone scientist outside the Establishment.