The fossil record of South American short-faced bears (Ursidae, Tremarctinae)

Abstract

The present study includes a review of the geographic and stratigraphic distribution of short-faced bears (Ursidae, Tremarctinae) in South America. In addition, the authors discuss biogeographic hypotheses regarding the origin of South American tremarctines. The Tremarctinae subfamily is distributed exclusively in America, from Alaska to southern Patagonia. Its biochron comprises the temporal lapse between Late Miocene and recent times; the first record of Tremarctinae in North America corresponds to the Hemphillian and the last to the Rancholabrean. In South America, the first record corresponds to the Ensenadan. In the present day, it corresponds to the only living tremarctine, the 'Andean Bear,' but short-faced bears became extinct during the early Holocene. The extinction of short-faced bears in North and South America appears to have been approximately synchronous. Finally, the fossil record in South America indicates species turnover between the Ensenadan and Bonaerian, during which time the giant species Arctotherium angustidens was replaced by Arctotherium tarijense, Arctotherium bonaeriense, and Arctotherium vetustum (and probably Arctotherium wingei). q

Quaternary mammals from central Brazil (Serra da Bodoquena, Mato Grosso do Sul) and comments on paleobiogeography and paleoenvironments

“…Such procedure took into account the occurrence of extinct Quaternary mammals above 50 kg in the Mato Grosso do Sul, Brazilian Intertropical region, São Paulo, Rio Grande do Sul, Uruguay, Mesopotamian region, North central Argentina, South of Bolivia, Paraguay and Pampean region. In Table 1, we present a matrix of presence (1) and absence (0) of taxa in South American paleozoogeographical zones, identified to species level, based on Prado & Alberdi (1999), Bond et al (2001), Alberdi & Prado (2004), Carlini et al (2004), Noriega et al (2004), Zurita et al (2004Zurita et al ( , 2007Zurita et al ( , 2011, Soibelzon et al (2005Soibelzon et al ( , 2012, Salles et al (2006), Pitana & Ribeiro (2007), Scherer et al (2007), Scheffler et al (2010), Pitana (2011), Miño-Boilini (2012, Silva et al (2012), Zurita et al (2012) including the specimens herein identified. The cluster analysis was performed on binary matrix employing the clustering algorithm UPGMA (Average Linkage Clustering; Sokal & Michener, 1958) and the Euclidean similarity index using the software Past 3.14.…”

Ancient mitochondrial DNA reveals convergent evolution of giant short-faced bears (Tremarctinae) in North and South America

“…The oldest known Arctotherium specimens are giant-sized [3,8,10], suggesting either that their size evolution occurred very rapidly or that fossils from the early stages of Arctotherium evolution have not yet been recorded. Our molecular dating estimates are compatible with both possibilities.…”

Accessory protection structures in Glyptodon Owen (Xenarthra, Cingulata, Glyptodontidae)

“…After the Plio-Pleistocene boundary (subsequent to GABI), the top predator guild in the South America Ensenadan ecosystems included seven species: Theriodictis platensis Mercerat, Protocyon scagliorum Kraglievich, P. troglodytes (Lund) and Canis (?) gezi Kraglievich (Canidae: Prevosti, 2007), Smilodon populator, Panthera onca (Linnaeus) and Puma Jardine (Felidae: Soibelzon and Prevosti, 2007), and Arctotherium angustidens (Ursidae, Soibelzon, 2004;Soibelzon et al, 2005) (see Webb, 2006). The fast diversification of carnivore guild possibly led to the evolution of different strategies (e.g., behavioral, physiological, anatomical) in the potential prey (Soibelzon et al, 2009b).…”