Pleistocene mammals from the southern Brazilian continental shelf

Abstract

a b s t r a c tFossils of terrestrial mammals preserved in submarine environment have been recorded in several places around the world. In Brazil such fossils are rather abundant in the southernmost portion of the coast, associated to fossiliferous concentrations at depths up to 10 m. Here is presented a review of such occurrences and the first record of fossils in deeper areas of the continental shelf. The fossils encompass several groups of both extinct and extant mammals, and exhibit several distinct taphonomic features, related to the marine environment. Those from the inner continental shelf are removed and transported from the submarine deposits to the coast during storm events, thus forming large konzentrat-lagerstätte on the beach, called "Concheiros". The only fossils from deeper zones of the shelf known so far are a portion of a skull, a left humerus and of a femur of Toxodon sp. and a lower right molar of a Stegomastodon waringi, all collected by fishermen at depths around 20 m. The presence of fossils at great depths and distances from the present coastline, without signs of abrasion and far from areas of fluvial discharges does indicate that these remains have not been transported from the continent to the shelf, but have been preserved directly on the area that today correspond to the continental shelf. These remains indicate the existence of large fossiliferous deposits that have developed during periods of sealevel lowstand (glacial maxima) and have been submerged and reworked by the sea-level rise at the end of the last glaciation.

Geological constraints on mesoscale coastal barrier behaviour

“…Belknap and Kraft, 1985;Riggs et al, 1995). The profusion of fossil shark teeth in barrier sediments of North Carolina , and Pleistocene mammal bones on the Lagoa dos Patos barrier in Brazil (Lopes and Buchmann, 2011), testify to a portion of barrier sediment being derived from erosion of underlying sediments.…”

Curadoria do Acervo Paleontológico da Universidade Federal do Rio Grande

“…Em muitos afloramentos é notável a ocorrência de Ophiomorpha, associados à Callichirus sp. Fósseis de mamíferos pleistocênicos também são comumente encontrados em associação com os depósitos sedimentares desta barreira (Lopes & Buchmann, 2011;Lopes & Simone, 2012;Hubbe et al, 2013).…”

“…Os Notoungulata -Toxodontidae (LGP/E 0001-0277) são mamíferos pleistocênicos exclusivos da América do Sul, que se assemelham bastante com os rinocerontes atuais (Lopes and Buchmann 2011). Os registros deste grupo incluem principalmente dentes molares e incisivos, provenientes da região dos Concheiros do Albardão.…”

Description and interpretation of Cenozoic vertebrate ichnofossils in Rio Grande do Sul State, Brazil

“…The same reasoning may be applied to the fossorial paleovertebrates. The diggers of the tunnels of Boqueirão do Leão, therefore, need to be found among the South American paleovertebrates of the megafauna, defi ned as composed by the large mammals whose body mass exceeds a few hundreds of kg (Fariña & Vizcaíno, 1995 (Megatherium, Cuvier, 1796;Eremotherium Spillmann, 1948;Glossotherium Owen, 1840;Lestodon Gervais, 1855;Mylodon Owen, 1840;Catonyx Lund, 1839) and giant armadillos (Pampatherium Ameghino, 1875;Holmesina Simpson, 1930; Propraopus Ameghino, 1881) (Lopes & Buchmann, 2011). Among these taxa, those with morphological adaptations to dig are only the armadillos and the ground sloths (Bargo et al, 2000).…”