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

Abstract

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

“…The ones he carried out in Quaternary sediments of the Pampean Region were especially significant, because during his excavations, he developed a biostratigraphic and biochronological scheme that was advanced for his time. The scheme has been subject to multiple revisions and interpretations, important to understand the recent evolution of faunas in that region (e.g., Carrillo & Püschel, 2023;Carrillo-Briceño et al, 2023;Christen et al, 2023;Kerber, 2023;Ruiz-Ramoni et al, 2023;Voglino et al, 2023). In his collections Roth located each of the remains he found in his stratigraphic scheme, thus allowing the formation of faunal aggregates on which the prevailing past environmental conditions were interpreted.…”

Santiago Roth and his scientific legacy: a reappraisal of the Swiss collections

“…The other eight articles focus on the systematics of Pampean Pleistocene mammals, principally based on specimens from Catalogue N°5 of Zurich but also featuring fossils in other European institutions that possess material originally collected by Roth (Geneva and Denmark). These chapters cover xenarthrans (Le Christen et al, 2023), Nearctic and native South American ungulates (Carrillo-Briceño et al, 2023;Carrillo & Püschel, 2023;Püschel & Martinelli, 2023), carnivorans (Ruiz-Ramoni et al, 2023), rodents (Kerber, 2023), and human remains (Menéndez et al, 2023), reviewing and updating the taxonomy of the specimens and exploring specific aspects of their anatomy and palaeobiology. We invite readers to explore the contributions in this volume, to immerse themselves in the works and times of Santiago Roth, and to re-discover his discoveries that continue to inspire new generations of researchers.…”