Co-occurrence of mylodontid sloths and insights on their potential distributions during the late Pleistocene

Abstract

Species distribution models (SDMs) for the last interglacial (LIG), the global last glacial maximum (LGM) and the Holocene climatic optimum (HCO) were generated for three extinct South American Pleistocene mylodontid giant sloths, Glossotherium robustum, Lestodon armatus and Mylodon darwinii. They are recorded co-occurring in some localities including Arroyo del Vizcaíno site (AdV) in Uruguay. Co-occurrence records were studied based on the overlap of their generated areas of potential distributions, and compared with the available biome reconstructions of South America during the LGM to analyze their distribution patterns, ecological requirements and possible interactions between them. Our results suggest that these sloths could have co-existed mainly in the Chaco-Paraná Basin and the plains in the Río de la Plata area. Areas of high suitability were observed for submerged parts of the continental shelf that were exposed during the LGM showing an overall increase in potential habitat compared to the LIG and HCO. This suggests that there was a drastic reduction in total available areas of preferred habitat at the end of the Pleistocene. The co-occurrence of these sloths at the AdV site suggests the presence of vegetation indicative of mainly open, cold to temperate habitats but with mixed patches typical of humid climates.

The distribution of the guanaco (Lama guanicoe) in Patagonia during Late Pleistocene–Holocene and its importance for prehistoric human diet

“…Although both data types, bioclimatic layers and occurrence records, are important to estimate the model, the final predicted distribution is made by projecting the model onto the bioclimatic layers (Elith and Leathwick, 2009). This approach has been extensively applied in ecology, biogeography and conservation biology for studying the distribution of extant species (Elith and Leathwick, 2009; Hao et al, 2019), and more recently in paleontology (e.g., Varela and Fariña, 2016; Villavicencio et al, 2019). However, beyond its potential utility for the study of the distribution of species in the past and the growing availability of detailed paleo-bioclimatic reconstruction (Brown et al, 2018; Fordham et al, 2017), species distribution models have not been widely employed in archaeology to estimate the distribution of main human prey (for an exception see Politis et al, 2011).…”

“…Species distribution is modeled using a maximum entropy approach ( maxent ; Phillips et al, 2006, 2017), which uses environmental layers or bioclimatic raster files and geo-referenced occurrence records to estimate a model that predicts the suitability conditions for the species presence in each raster pixel (Hijmans et al, 2017). We employ this approach because is widely used in paleoecology (e.g., Politis et al, 2011; Varela and Fariña, 2016; Villavicencio et al, 2019) and is considered one of the most effective methods for species distribution modeling with presence-only data (Elith et al, 2010; Espinosa et al, 2018; Phillips et al, 2006; Politis et al, 2011). Additionally, we explore the spatial variation in the importance of guanaco for human diet in Patagonia during the end of the Late Pleistocene and the main time periods of the Holocene.…”

Resolving the phylogenetic position of Darwin's extinct ground sloth ( Mylodon darwinii ) using mitogenomic and nuclear exon data

“…Like the vast majority of the Pleistocene megafauna, M. darwinii went extinct at the Pleistocene/Holocene boundary, approximately 10 000 years ago [ 2 ]. Numerous subfossils of M. darwinii have been found across the South American southern cone [ 3 ], including the famous Mylodon Cave (Cueva del Milodón, Ultima Esperanza, Chile). This cave derives its name from the numerous and exquisitely preserved remains of this ground sloth found inside.…”

Unexpected inhibitory cascade in the molariforms of sloths (Folivora, Xenarthra): a case study in xenarthrans honouring Gerhard Storch’s open-mindedness

“…1). The largest mylodontid Lestodon armatus was selected because it is probably the most abundant ground sloth found in Pleistocene deposits of Uruguay (Fariña et al 2014, Varela andFariña 2016), along with the large number of remains found in Argentina and Brazil, and because, despite this, it remains relatively little studied. We also collected data from sloth genera covering all sloth families from a revision of the literature, as well as published images and measurements of museum specimens (Tab.…”