Young Darwin and the ecology and extinction of pleistocene south american fossil mammals

Abstract

Duringhis two years in South America Charles Darwin became fascinated not only with the lush vegetation of Brazil, but also with the gigantic Pleistocene mammals that hefound in the drier areas of Uruguay, and in the pampas and Patagonian coast of Argentina. These findings included various ground sloths and glyptodonts among xenarthrans, and hoofed herbivoreslike Toxodon and Macrauchenia, in addition to horses and smallrodents. He concluded that the general assumption that large animals requireluxuriant vegetation was false and that vitiated the reasoning of geologists onsome aspects of Earth's history. He also reflected on the evident changes that occurred in the continent, the extinct fauna of which suggested to him ananalogy to southern parts of Africa. He wondered about our ignorance of biological traits inextinct creatures and the reasons for their extinction. Thus, not only did Darwin inspire phylogeneticstudies on fossil mammal lineages, he also opened a gate to the research ontheir behaviour, physiology and extinction; i.e., their palaeobiology. Whereas the first approach was largely developed in South America beginning about thesecond half of the 19^th century due to the intellectual influence of Florentino Ameghino, palaeobiology became a much more recent line of work, inapparent relation to innovations in methodology and technology. This contribution provides an overview of recent contributions on the palaeobiology of Pleistocene fossil mammals of South America as attempts to provide answers for Darwin's questions.