Splendid oddness: revisiting the curious trophic relationships of South American Pleistocene mammals and their abundance

Abstract

The South American Pleistocene mammal fauna includes great-sized animals that have intrigued scientists for over two centuries. Here we intend to update the knowledge on its palaeoecology and provide new evidence regarding two approaches: energetics and population density and relative abundance of fossils per taxa. To determine whether an imbalance exists, population density models were applied to several South American fossil faunas and the results compared to those that best describe the palaeoecology of African faunas. The results on the abundance study for Uruguay and the province of Buenos Aires during the Lujanian stage/age reveal that bulk-feeding ground sloths (Lestodon and Glossotherium) were more represented in the first territory, while the more selective Scelidotherium and Megatherium were more abundant in the second. Although the obtained values were corrected to avoid size-related taphonomic biases, linear regressions of abundance vs. body mass plots did not fit the expected either for first or second consumers. South American Pleistocene faunas behave differently from what models suggest they should. Changes in sea level and available area could account for these differences; the possibility of a floodplain in the area then emerged could explain seasonal changes, which would modify the calculations of energetics and abundance.

Pleistocene megafaunal extinctions and the functional loss of long‐distance seed‐dispersal services

“…We performed 100 simulations for each species to encompass uncertainty. To investigate how megafaunal extinction changed the potential for seed dispersal of large-seeded plants we simulated seed dispersal by populations of each of the large mammalian species present in five different regions in South America during the late Pleistocene: southern Brazil (França et al 2015), São Raimundo Nonato in northeastern Brazil (Guérin 1991), central Chile (Encina 2015), Santa Elena peninsula in Ecuador (Lindsey and Lopez 2015) and the Pampean region in Argentina (Fariña et al 2014). Data for each assemblage is summarized in Supplementary material Appendix 1 Table A4.…”

Community Structure of South American Carnivores in the Past and Present

“…Fariña's (1996) method was then reused by Vizcaíno et al (2010) to propose that some of the Santa Cruz Formation (late early Miocene) mammal assemblages were out of balance, with proportionally few Sparassodonta. In the same way, Fariña et al (2014) went further and included new Pleistocene mammal assemblages in their analysis, finding new evidence to support the scenario described in Fariña (1996). However, since Vizcaíno et al (2010) and Fariña et al (2014) did not correct the methodological biases and errors pointed out by Prevosti and Vizcaíno (2006), their conclusions about the faunal unbalance may not be reliable.…”

A Fossil Bone of a Giant Ground Sloth from the Last Millennium of the Pleistocene: New Data from Salto Department, Uruguay

“…The Lestodon armatus is an extinct species of megafaunal ground sloth that inhabited South America (e.g. Deschamps et al, 2000, Czerwonogora, 2010Fariña et al, 2014, Ubilla et al, 2016among others).…”

“…According to the last phylogenetic study (Boscaini et al, 2019), it was a bulk-feeding mega-mammal, measuring ~4.5 meters from nose to tail tip ( Figure 2) and estimated to have weighed over 2 tons (Fariña et al, 2014). Remains of this kind of ground sloth were found in the Pleistocene deposits of Venezuela, Brazil, Bolivia, Paraguay, Argentina and Uruguay (Czerwonogora, 2010;Fariña et al, 2014), but some records date back to the Early Pliocene in Argentina (Deschamps et al, 2000). Particularly in northern Uruguay, the Lestodon armatus bones come from the Sopas Formation, a Late Pleistocene continental unit including trace fossils, woods, fresh-water mollusks, and as illustrated in Figure 3, vertebrates with mammals as the predominant taxa (Ubilla et al, 2016, Table 4).…”