Supplemental Material for 'Exceptional skull of Huayqueriana (Mammalia, Litopterna, Macraucheniidae) from the late Miocene of Argentina : anatomy, systematics, and paleobiological implications. (Bulletin of the American Museum of Natural History, no. 404)'
“…Instead, Guérin and Faure (2004) deemed the observed variation between X. bahiense and M. patachonica species-level variation without properly testing such an assumption. Indeed, other studies (e.g., Scherer et al, 2009) do not follow the taxonomic arrangement of Guérin and Faure (2004), and further phylogenetic studies of Schmidt and Ferrero (2014) and Forasiepi et al (2016) refuted the idea by revealing consistent morphological features that differ between the two monospecific genera.…”
Abstract.-Litopterna is represented in the Pleistocene of the Brazilian Intertropical Region by a monospecific genus of Macraucheniidae, Xenorhinotherium. Although most of the knowledge about this family is derived from the dentition, some dental features still remain unknown. This study describes the eruption sequence of permanent dentition and classifies the hypsodonty status of X. bahiense. The specimens studied are from Toca dos Ossos, a limestone cave located in Bahia State. We perform qualitative macroscopic analysis to describe the eruption dental sequence. Additionally, we perform quantitative analysis to determine the hypsodonty index. The dental eruption sequence of the juvenile specimen is M1, M2, I1, I2, M3, I3, P1, P2, P3, and P4. In addition, the analysis of tooth wear in adult specimens provides similar results. The hypsodonty index assigns a mesodont tooth crown for X. bahiense. The dental eruption sequence is most similar to a rapid-growth extant mammal. Moreover, our results do not support afrotherian-like delayed dental eruption to Litopterna. The hypsodonty index can be related to data on vegetation of the Brazilian Intertropical Region and the shape of the premaxilla of X. bahiense, both of which suggest a browsing diet for this macraucheniid.
“…Instead, Guérin and Faure (2004) deemed the observed variation between X. bahiense and M. patachonica species-level variation without properly testing such an assumption. Indeed, other studies (e.g., Scherer et al, 2009) do not follow the taxonomic arrangement of Guérin and Faure (2004), and further phylogenetic studies of Schmidt and Ferrero (2014) and Forasiepi et al (2016) refuted the idea by revealing consistent morphological features that differ between the two monospecific genera.…”
Abstract.-Litopterna is represented in the Pleistocene of the Brazilian Intertropical Region by a monospecific genus of Macraucheniidae, Xenorhinotherium. Although most of the knowledge about this family is derived from the dentition, some dental features still remain unknown. This study describes the eruption sequence of permanent dentition and classifies the hypsodonty status of X. bahiense. The specimens studied are from Toca dos Ossos, a limestone cave located in Bahia State. We perform qualitative macroscopic analysis to describe the eruption dental sequence. Additionally, we perform quantitative analysis to determine the hypsodonty index. The dental eruption sequence of the juvenile specimen is M1, M2, I1, I2, M3, I3, P1, P2, P3, and P4. In addition, the analysis of tooth wear in adult specimens provides similar results. The hypsodonty index assigns a mesodont tooth crown for X. bahiense. The dental eruption sequence is most similar to a rapid-growth extant mammal. Moreover, our results do not support afrotherian-like delayed dental eruption to Litopterna. The hypsodonty index can be related to data on vegetation of the Brazilian Intertropical Region and the shape of the premaxilla of X. bahiense, both of which suggest a browsing diet for this macraucheniid.
“…More recently, some studies focusing on the cranial anatomy, including the petrosal and inner ear anatomy of other litopterns, have used specimens of Ma. patachonica in their comparisons revealing previously unknown aspects of macraucheniid’s cranial evolution (Billet et al, 2015 ; Dozo et al, 2023 ; Fernández-Monescillo, 2020 ; Forasiepi et al, 2016 ). Fig.…”
Section: Systematic Palaeontologymentioning
confidence: 88%
“…Notoungulata includes two major sub-clades, Toxodontia (toxodonts and allies) and Typotheria, both of which have representatives that survived until the Late Pleistocene (Billet, 2011 ; Croft et al, 2020 ; Deraco & García-López, 2016 ). The two most diverse subclades within Litopterna are Proterotheriidae and Macraucheniidae, which also survived until the Late Pleistocene (Carrillo et al, 2023 ; Forasiepi et al, 2016 ; McGrath et al, 2020a ; Püschel et al, 2023 ; Schmidt, 2015 ; Villafañe et al, 2006 ). Moreover, the Late Pleistocene Pampean record of Toxodon Owen, 1837 (Notoungulata) and Macrauchenia Owen, 1838 (Litopterna) provided key data that helped to clarify the phylogenetic relationships of these two extinct clades within placentals.…”
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.
“…Litopterna is a diverse clade of SANUs recorded in South America from at least the late Paleocene (Peligran SALMA [Gelfo et al, 2009], although possibly they were present since the Tiupampan SALMA [Muizon and Cifelli, 2000]), to the late Pleistocene (Bond et al, 2001). Several clades are recognized within Litopterna: Protolipternidae, Notonychopidae, Adianthidae, Macraucheniidae, and Proterotheriidae (Cifelli, 1983(Cifelli, , 1993Schmidt, 2015;Forasiepi et al, 2016). The Sparnotheriodontidae has been variably treated as "Condylarthra" (Cifelli, 1983(Cifelli, , 1993 or as a member of Litopterna (Soria, 2001).…”
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