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The coastal plain of the state of Rio Grande do Sul, in southern Brazil, includes four barrier-lagoon depositional systems formed by successive Quaternary sea-level highstands that were correlated to marine isotope stages (MIS) 11, 9, 5 and 1, despite the scarcity of absolute ages. This study describes a sea-level highstand older than MIS 5, based on the stratigraphy, ages and fossils of the shallow marine facies found in coastal barrier (Barrier II). This facies outcrops along the banks of Chuí Creek, it is composed of fine, well-sorted quartz sand and contains ichnofossils Ophiomorpha nodosa and Rosselia sp., and molluscan shells. The sedimentary record indicates coastal aggradation followed by sea-level fall and progradation of the coastline. Thermoluminescence (TL) and electron spin resonance (ESR) ages from sediments and fossil shells point to an age of ~220 ka for the end of this marine transgression, thus correlating it to MIS 7 (substage 7e). Altimetric data point to a maximum amplitude of about 10 meters above present-day mean sea-level, but tectonic processes may be involved. Paleoceanographic conditions at the time of the highstand and correlations with other deposits in the Brazilian coasts are also discussed.

-New records of rodents from the late Pleistocene Chuí Creek, Rio Grande do Sul State, southern Brazil, are here described. A partial dentary with fragmented cheek teeth is identified as Chinchillidae, Lagostomus Brookes cf. L. maximus (Desmarest). Other two specimens are identified as cheek teeth of Dolichotinae indet. (Caviidae). Pleistocene fossils of Lagostomus were previously reported for Argentina and Uruguay. The material of Lagostomus from Chuí Creek represents the first confidently record of this taxon Brazil. Pleistocene fossil remains of Dolichotinae have been found in Argentina, Uruguay and other areas of southern Brazil, though the Brazilian find lack precise stratigraphic information. These new records widen the paleobiogeographic distribution of Lagostomus and confirm the presence of Dolichotinae during the late Pleistocene of southern Brazil.Key words: Lagostomus, Lagostominae, Dolichotinae, Chuí Creek, Rio Grande do Sul, Quaternary.RESUMO -Este trabalho reporta novos materiais de roedores provenientes dos depósitos fossilíferos do arroio Chuí (Rio Grande do Sul, sul do Brasil). O material de Chinchillidae é identificado como Lagostomus Brookes cf. L. maximus (Desmarest) e é representado por um dentário esquerdo faltando sua região posterior, com o incisivo preservado e a série p4-m3 fragmentada. Os outros dois espécimes são identificados como molariformes de Dolichotinae indet. (Caviidae). Os fósseis de Lagostomus durante o Pleistoceno estavam restritos a Argentina e Uruguai. O material aqui reportado caracteriza o primeiro registro seguro deste táxon no Brasil. Fósseis de Dolichotinae têm sido encontrados em depósitos pleistocênicos da Argentina, Uruguai e sul do Brasil, porém este último provém de uma localidade sem contexto estratigráfico preciso. Desta forma, estes novos registros ampliam a distribuição paleobiogeográfica de Lagostomus e confirmam a presença de Dolichotinae durante o Pleistoceno final do sul do Brasil. Palavras-chave:Lagostomus, Lagostominae, Dolichotinae, arroio Chuí, Rio Grande do Sul, Quaternário.

-Intertropical Pleistocene taxa of dasypodids and pampatheriids are reported for the Lagoon-Barrier III System (Arroio Chuí locality) and for the Touro Passo Formation (Ponte Velha I locality), both from Rio Grande do Sul State, southern Brazil. The record of pampatheriids includes new specimens that confirm the presence of Pampatherium humboldti in the Arroio Chuí assemblage. Material previously assigned to Holmesina majus is identified as H. paulacoutoi. The record of dasypodids includes a large-sized specimen of the genus Dasypus, represented by an isolated pelvic buckler osteoderm, closely related to Dasypus (Hyperoambon) kappleri, and of Propraopus sulcatus, represented by isolated moveable and fixed osteoderms. This southernmost Brazilian record of P. sulcatus extends their distribution by about 2200 km from Lagoa Santa (Minas Gerais State, Brazil). The first record of P. sulcatus also includes specimens previously referred to as Propraopus cf. grandis from the Touro Passo Formation. Propraopus sulcatus differs from P. punctatus and P. grandis in having: osteoderms with wrinkled external surface, with wide and relatively deep sulci; principal figure plane, ranging from subcircular to hexagonal in fixed osteoderms; and moveable osteoderms with principal sulci forming a lageniform figure, and with four to five larger foramina distributed on the posterior half of these sulci. The late Pleistocene mammals of the coastal province and western Rio Grande do Sul were previously considered closely related to those of the Pampean region of Argentina. However, the presence of intertropical mammals in southern Brazil (Arroio Chuí locality and Touro Passo Formation) mixed with Pampean representatives, corroborates the proposal of a close paleobiogeographic relation with assemblages of northern Uruguay and Argentine Mesopotamia.

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