Cástor Cartelle

Systematic revision of tropical Brazilian scelidotheriine sloths (Xenarthra, Mylodontoidea)

ABSTRACT The analysis of recently recovered ground sloth remains from Minas Gerais, Bahia, and Piauí (Brazil) results in a major reinterpretation of the Scelidotheriinae and Megalonychidae of tropical Brazil. Among the specimens collected from Lagoa Santa (Minas Gerais) by Lund during the first half of the 19th century are skeletal elements attributable to two scelidotheriine species, as Lund himself determined and Winge corroborated. This is in contrast to the interpretation of these remains as representing a scelidotheriine and the postcranial remains of a peculiar megalonychid, as most authors, following Hoffstetter, have believed. A new combination is proposed here for one of the species. Another scelidotheriine recently described from Piauí by Guérin and Faure is a synonym of this species.

Recent Advances on Variability, Morpho-Functional Adaptations, Dental Terminology, and Evolution of Sloths

The occasion of the Xenarthra Symposium during the ICVM 9 meeting allowed us to reflect on the considerable advances in the knowledge of sloths made by the “X-community” over the past two decades, particularly in such aspects as locomotion, mastication, diet, dental terminology, intraspecific variation, sexual dimorphism, and phylogenetic relationships. These advancements have largely been made possible by the application of cladistic methodology (including DNA analyses) and the discovery of peculiar forms such as Diabolotherium, Thalassocnus, and Pseudoglyptodon in traditionally neglected areas such as the Chilean Andes and the Peruvian Pacific desert coast. Modern tree sloths exhibit an upside-down posture and suspensory locomotion, but the habits of fossil sloths are considerably more diverse and include locomotory modes such as inferred bipedality, quadrupedality, arboreality or semiarboreality, climbing, and an aquatic or semi-aquatic lifestyle in saltwater. Modern tree sloths are generalist browsers, but fossil sloths had browsing, grazing, or mixed feeding dietary habits. Discovery of two important sloth faunas in Brazil (Jacobina) and southern North America (Daytona Beach and Rancho La Brea) have permitted evaluation of the ontogenetic variation in Eremotherium laurillardi and the existence of possible sexual dimorphism in this sloth and in Paramylodon harlani. A new dental terminology applicable to a majority of clades has been developed, facilitating comparisons among taxa. An analysis wherein functional traits were plotted onto a phylogeny of sloths was used to determine patterns of evolutionary change across the clade. These analyses suggest that megatherioid sloths were primitively semiarboreal or possessed climbing adaptations, a feature retained in some members of the family Megalonychidae. Pedolateral stance in the hindfoot is shown to be convergently acquired in Mylodontidae and Megatheria (Nothrotheriidae + Megatheriidae), this feature serving as a synapomorphy of the latter clade. Digging adaptations can only be securely ascribed to scelidotheriine and mylodontine sloths, and the latter are also the only group of grazing sloths, the remainder being general browsers.

A Paleogeographic Overview of Tropical Fossil Sloths: Towards an Understanding of the Origin of Extant Suspensory Sloths?

Modern sloths are among the more characteristic mammals of South and Central American faunas. Recent discovery in four Paleogene, 22 Neogene, and dozens of Pleistocene fossiliferous localities in the tropics has revealed an unexpected paleobioversity constituted by some 81 fossil sloth species. Probably originating in southern South America near the Eocene/Oligocene transition, sloths were represented in the tropics during the late Oligocene by Pseudoglyptodon, Mylodontidae, and Megalonychidae. The latter occupied the West Indies between at least the late early Miocene and late Pleistocene, and two mylodontid clades, Octodontobradyinae and Urumacotheriinae, were characteristic of Amazonian localities from the Colhuehuapian and the Laventan periods, respectively, until the end of the Miocene. Megatheriinae and Nothrotheriidae appeared during the middle Miocene, colonizing the tropics and then North America, where Mylodontidae and Megalonychidae had already been present since the early late Miocene. Nothrotheriids are more abundant and diversified during the late Miocene in the tropics than in southern South America. Remains closely related to either of the modern sloths are absent from the fossil record, including those in the tropics. The characteristic suspensory posture of Bradypus and Choloepus appeared independently and likely after the Miocene epoch, and thus well after the hypothesized split suggested by molecular studies of the respective clades of these genera. Given their current widespread distribution in and reliance on the tropics, prospecting efforts for the direct fossil kin of suspensory sloths should concentrate on deposits in the Amazonian region, as this area has shown promise in producing fossil sloths.

New Pleistocene remains of megalonychid ground sloths (Xenarthra: Pilosa) from the intertropical Brazilian region

Abstract. The Pleistocene fossil sloth Australonyx aquae De Iuliis, Cartelle, and Pujos, 2009 (Mammalia, Xenarthra, Megalonychidae) was described from the intertropical region of Brazil. However, its mandible was not known and only cursory descriptions of the ear ossicles were included. The mandible was subsequently recognized among the remains originally collected from the type locality, and belongs to the holotype individual. As a particularly important skeletal element for specific recognition, it requires description to complement our understanding of this species. The ossicles, usually poorly represented in the fossil record, require further description to allow differentiation from those of other sloths. Comparisons of the mandible and ossicles are conducted with homologous elements of the contemporaneous and sympatric Ahytherium aureum Cartelle, De Iuliis, and Pujos, 2008, the only other megalonychid sloth known from intertropical Brazil, and reinforce the distinction between these two species detailed in their initial descriptions. Comparisons with other sloths (e.g., Acratocnus, Megalonyx, Neocnus) also reveal differences with Au. aquae in such features as form and size of the caniniform tooth, angular process, and mandibular condyle. Differences among the malleus and incus of Au. aquae and several species of other sloth clades reveal clade level distinctions among Megatheriidae, Nothrotheriidae, and Megalonychidae. A well-preserved skull from the Brazilian state of Rondônia is noted as probably belonging to Au. aquae. This skull cannot be assigned formally to this species because it is not deposited in a recognized institution, but it does extend considerably the known range of the species.

Cranial and dental studies of Glossotherium robustum (Owen, 1842) (Xenarthra: Pilosa: Mylodontidae) from the Pleistocene of southern Brazil

Pitana, V.G., Esteban, G.I., Ribeiro, A.M. & Cartelle, C. 2013. Cranial and dental studies of Glossotherium robustum (Owen, 1842) (Xenarthra: Pilosa: Mylodontidae) from the Pleistocene of southern Brazil. Alcheringa, 1–16. ISSN 0311-5518. Mylodontine ground sloths were studied from several Pleistocene localities of Rio Grande do Sul State: São Gabriel (central region), Quaraí, Uruguaiana and Alegrete (western region) and Santa Vitória do Palmar (coastal region) municipalities. The cranial and mandibular material is assigned to Glossotherium robustum based on the enlargement of the anterior portion of the maxilla, a rounded and ventrolaterally arched fossa for the estylohyal, an elliptical occipital condyle, a spatulate symphyseal region of the mandible, together with the size and degree of lobulation of the teeth. Comparison with specimens from the Pampean region of Argentina, western Uruguay and northeastern Brazil revealed that the Rio Grande do Sul material is most similar morphologically to that of the Pampean region of Argentina and Uruguay. These southern specimens are morphologically distinct from Pleistocene material from tropical Brazil assigned to Glossotherium sp. The Pleistocene records of G. robustum indicate that this taxon was widely distributed between 20°S and 40°S spanning Argentina, Brazil, Bolivia, Chile, Uruguay and Paraguay, whereas Glossotherium sp. was restricted to latitudes <30°S.

Methodological innovations for the study of irreplaceable samples reveal giardiasis in extinct animals (Nothrotherium maquinense and Palaeolama maior)

The use of diagnostic methods that prevent irreplaceable samples (from museum collections, archaeological and paleontological samples) of being consumed or that increase their yield is relevant. For museum collections, archaeological and paleontological samples it is essential to conserve samples, subsamples or portions for future research. We are addressing methods for conservation of irreplaceable samples that could be fully consumed. Innovations in methodologies that are used in studies of Paleoparasitology and Paleomicrobiology will contribute to the preservation of collections. Therefore, to the development of archaeology and paleontology in the future, we evaluated whether the discarded material of the immunochromatography test could be used for molecular diagnosis and vice versa. We used a genotyped experimental coprolite positive for Giardia duodenalis. The diagnosis was positive for giardiasis in both cases. This methodology can be corroborated with the coprolite of a Paleolama maior (extinct llama) previously diagnosed for G. duodenalis with an immunoenzymatic test. The residue of the pre-digestion step of the DNA extraction before adding Proteinase K was confirmed positive with the immunochromatographic test. Also, the DNA extraction residue from a coprolite of Nothrotherium maquinense (ground sloth) was tested positive with immunochromatographic test for G. duodenalis. These are the oldest findings for G. duodenalis confirming that this intestinal parasite occurred among Northeastern Brazilian Megafauna animals from the late Pleistocene period, correlated to human occupation. The relevance of these results will allow the study by different methodological approaches from a small amount of material, reusing discarded materials.

Dental eruption sequence and hypsodonty index of a Pleistocene macraucheniid from the Brazilian Intertropical Region

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.