The Fossil Mammals Collected by Charles Darwin in South America during His Travels on Board the Hms Beagle

During the first two years of his voyage aboard HMS Beagle, Charles Darwin collected a considerable number of fossil mammals from various localities in Argentina and Uruguay. Among these remains are those of large mammals that Darwin informally assigned to Megatherium and Mastodon, the only large taxa then known for South America, and of small and mediumsized mammals that Darwin recognized as representing at least two rodents and a horse. The study of Darwin's collection was entrusted to Richard Owen, who described eleven taxa between 1837 and 1845, including the six following ones: Toxodon platensis, Macrauchenia patachonica, Equus curvidens, Scelidotherium leptocephalum, Mylodon darwini and Glossotherium sp. This contribution provides a synthesis of Darwin's preliminary assignments and evaluates the reasons that led him to recognize only megatheres and mastodonts for the large fossil remains. Also, it discusses the current taxonomic status of the taxa described or erected by Owen between 1837 and 1845 and the influence that Owen's taxonomic and phylogenetic conclusions had on the development of Darwin's ideas on evolution.