 Charles Darwin's publication of the "On the Origin of Species" in 1859 was a watershed event in all the life sciences, especially paleontology.Fossils had played a role in the development of Darwin's theory.In particular he had been impressed by fossils he had collected in South America during the voyage of the Beagle of giant armadillos, giant sloths, and what at the time he thought were giant llamas that seemed to be related to species still living on the continent in modern times.