Pampean megamammals in Europe: the fossil collections from Santiago Roth

Pleistocene South American native ungulates (Notoungulata and Litopterna) of the historical Roth collections in Switzerland, from the Pampean Region of Argentina

The fossil collections made by early explorers in South America have been fundamental to reveal the past diversity of extinct mammals and unravel their evolutionary history. One important early explorer in South America was the Swiss-Argentine palaeontologist Kaspar Jacob Roth, known as Santiago Roth (1850, Herisau, Switzerland-1924, Buenos Aires, Argentina), who made significant collections of fossil mammals that are housed in museums in Europe and Argentina. The important collections of Roth in Switzerland include iconic Pleistocene megafauna from the Pampean Region (Argentina). The palaeontological significance of the Pampean Region relies on its abundant record of fossil vertebrates that documents diversity dynamics and paleoenvironmental change in southern South America, serving as the basis for the South American biostratigraphical scale of the late Neogene and Quaternary. The South American native ungulates (SANUs) were hoofed placental mammals that radiated in South America. The clades Notoungulata and Litopterna include, among others, the last representatives of SANUs megafauna in the continent. We revise and describe for the first time the SANUs specimens from the Pampean Region of the Roth collections in Switzerland. The collections include two species of notoungulates (Toxodon cf. T. platensis and Mesotherium cristatum) and one litoptern species (Macrauchenia patachonica). The occurrences are restricted to the early and middle Pleistocene (pre-Lujanian Stages/Ages). Although the SANUs diversity in the Roth collections is low in comparison with other groups (e.g., xenarthrans), some of the specimens are very complete, including skulls and postcranial remains. The completeness of the Ma. patachonica material allows an update and reinterpretation of some of the details of the dentition and the postcranial skeleton of this iconic species. In addition to its historical importance, the SANU specimens from the Roth collections provide important information to study the paleobiology and evolution of South American megafauna and evaluate hypotheses about their extinction in the continent.

From fossil trader to paleontologist: on Swiss-born naturalist Santiago Roth and his scientific contributions

Roth's explorations, the resulting collections many now allocated in La Plata, Zurich, Geneva and Copenhagen, and his significant contributions in geological-especially stratigraphic-and paleontological topics, are a paradigmatic case for the global history of paleontology and for the Swiss migration history in Latin America. His work included the discovery of a diverse megafauna from the Pampean region, of sites and strata in Patagonia of paleontological significance, and the recognition of a group of endemic ungulate mammals, Notoungulata. Roth's discovery of a human skeleton associated with a glyptodont carapace is one of the first reports of the coexistence of humans with the extinct fauna of the South American Quaternary. Roth became a renowned scholar at the Museo de La Plata, which was a leading scientific institution in the nation-making of Argentina, particularly in the expansion of the Patagonian frontier. He also kept strong ties with his native Switzerland, where late in his adult life he obtained some formal training and tried to attract other Swiss nationals to work in natural sciences in Argentina. His biography sheds light about the circumstances of his scientific collection and career in the interstices between amateur and professional science, modernity and imperialism at the turn of the twentieth century.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13358-023-00282-6.