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Miocene deposits of South America have yielded several species-rich assemblages of caviomorph rodents. They are mostly situated at high and mid- latitudes of the continent, except for the exceptional Honda Group of La Venta, Colombia, the faunal composition of which allowed to describe the late middle Miocene Laventan South American Land Mammal Age (SALMA). In this paper, we describe a new caviomorph assemblage from TAR-31 locality, recently discovered near Tarapoto in Peruvian Amazonia (San Martín Department). Based on mammalian biostratigraphy, this single-phased locality is unambiguously considered to fall within the Laventan SALMA. TAR-31 yielded rodent species found in La Venta, such as the octodontoid Ricardomys longidens Walton, 1990 (nom. nud.), the chinchilloids Microscleromys paradoxalis Walton, 1990 (nom. nud.) and M. cribriphilus Walton, 1990 (nom. nud.), or closely-related taxa. Given these strong taxonomic affinities, we further seize the opportunity to review the rodent dental material from La Venta described in the Ph.D. volume of Walton in 1990 but referred to as nomina nuda. Here we validate the recognition of these former taxa and provide their formal description. TAR-31 documents nine distinct rodent species documenting the four extant superfamilies of Caviomorpha, including a new erethizontoid: Nuyuyomys chinqaska gen. et sp. nov. These fossils document the most diverse caviomorph fauna for the middle Miocene interval of Peruvian Amazonia to date. This rodent discovery from Peru extends the geographical ranges of Ricardomys longidens, Microscleromys paradoxalis, and M. cribriphilus, 1,100 km to the south. Only one postcranial element of rodent was unearthed in TAR-31 (astragalus). This tiny tarsal bone most likely documents one of the two species of Microscleromys and its morphology indicates terrestrial generalist adaptations for this minute chinchilloid.

-HOLOCENE SIGMODONTINE RODENTS (MAMMALIA, RODENTIA, CRICETIDAE) FROM RIO GRANDE DO SUL, BRAZIL -THE SITE RS-TQ-58: AFONSO GARIVALDINO RODRIGUES. We present the sigmodontine assemblage from lower and middle Holocene recorded in the archaeological site RS-TQ-58: Afonso Garivaldino Rodrigues (County of Brochier, State of Rio Grande do Sul). A total of 16 species are detected from the study of 572 specimens, about half of which belonging to the tribe Akodontini. The assemblage recorded include species which typically inhabit open areas (e.g. Calomys sp., Gyldenstolpia sp., Kunsia tomentosus) and also several considered as forest dewellers (e.g. Delomys sp., Juliomys sp., Sooretamys angouya). Necromys obscurus, a sigmodontine today restricted to Central Argentina and Southern Uruguay, is abundantly recorded in Garivaldino and reported for the first time to the Quaternary from Brazil. Thaptomys nigrita and Wilfredomys oenax have in Garivaldino their first records to the Holocene from Rio Grande do Sul State. Compared to the recent assemblage of sigmodontine rodents recorded in Rio Grande do Sul, Pseudoryzomys simplex, K. tomentosus, N. obscurus and Gyldenstolpia sp. became regionally extinct. The sigmodontine assemblage detected in Garivaldino is richest than a previously studied one from Pilger site. The evidence of both sites reflects changes in the species composition, which can be linked with a progressive transformation of the general landscape from mostly open grasslands to forests. Key words: lower Holocene, Necromys obscurus, Sigmodontinae, Thaptomys nigrita, Wilfredomys oenax.RESUMO -Apresentamos a assembleia de sigmodontíneos do Holoceno inferior e médio registrada no sítio arqueológico RS-TQ-58: Afonso Garivaldino Rodrigues (Município de Brochier, Estado do Rio Grande do Sul). Um total de 16 espécies foram detectadas pelo estudo de 572 espécimes, sendo quase metade destes pertencente a tribo Akodontini. Esta assembleia inclui espécies tipicamente de áreas abertas (e.g. Calomys sp., Gyldenstolpia sp., Kunsia tomentosus) e outras consideradas florestais (e.g. Delomys sp., Juliomys sp., Sooretamys angouya). Necromys obscurus, sigmodontíneo atualmente restrito à Argentina Central e sul do Uruguai, está presente de forma abundante no sítio Garivaldino e é registrado pela primeira vez para o Quaternário do Brasil. Thaptomys nigrita e Wilfredomys oenax tem seus primeiros registros para o Holoceno do Estado do Rio Grande do Sul. Em comparação com a assembleia atual de roedores sigmodontíneos conhecida para o Rio Grande do Sul, Pseudoryzomys simplex, K. tomentosus, N. obscurus e Gyldenstolpia sp. tornaram-se regionalmente extintos. A assembleia de sigmodontíneos registrada no Garivaldino é mais rica do que outra previamente estudada proveniente do sítio Pilger. A evidência de ambos os sítios reflete mudanças na composição de espécies, a qual pode estar relacionada com uma transformação progressiva da paisagem, de campos abertos para florestas. Palavras-chave:Holoceno inferior, Necromys obscurus, Sigmodontin...

Understanding resource utilization and economic diversification amongst Holocene hunter‐gatherers in southern Brazil requires in‐depth taphonomic analysis of faunal assemblages. Three Early to Late Holocene archaeological sites (Garivaldino, Pilger and Sangão) in Rio Grande do Sul State, southern Brazil, revealed large assemblages of small mammal (˂1 kg) remains, composed mainly of rodents. To appreciate depositional processes of fauna in relation to human consumption, taphonomic attributes and processes were evaluated. The results indicated that the remains accumulated through different antemortem taphonomic pathways, apparently linked to the size and natural history of the species represented. The small‐ and medium‐sized (<150 g) cricetid rodents (e.g. Pseudoryzomys simplex and Sooretamys angouya) were represented by a low proportion of teeth with lightly digestive corrosion suggesting that they were derived from the predatory activity of owls, possibly Tyto alba. In contrast, large‐sized cricetids (>150 g; Kunsia tomentosus, Gyldenstolpia sp. and Holochilus sp.), and several caviomorph rodents with aggregated spatial distributions (Echimyidae (†Dicolpomys fossor, Phyllomys sp., †Clyomys riograndensis and †Euryzygomatomys mordax), Caviidae (Cavia sp.) and Ctenomyidae (Ctenomys sp.)) showed evidence of thermoalteration patterns and cut marks on bones, suggesting human exploitation. A postmortem depositional environment was deduced from dendritic and branched patterns of rootlet etching, apparent mostly at Garivaldino and Pilger. Polished areas and holes on bone surfaces, and impregnation of manganese showed moderate (Sangão) or low (Garivaldino and Pilger) incidence, pointing to water transport under moderate (Pilger) and low (Garivaldino and Sangão) energy over short distances. The results obtained here provide the first clear evidence of early human exploitation of small mammals in southern Brazil, suggesting a diversification of economies. In addition, as several of the recorded rodents are today regionally or biologically extinct, a preliminary discussion about the potential impact of humans on this process is provided.

A análise e identificação de pequenos mamíferos em egagropilos de coruja, em especial do gênero Tyto, são consideradas uma ferramenta útil e complementar na mastozoologia. No entanto, poucos estudos deste tipo têm sido desenvolvidos no sul do Brasil. Foram analisados os fragmentos cranianos e mandibulares de pequenos mamíferos encontrados em egagropilos de Tyto furcata coletados em sete localidades dos três estados do sul do país. Ao todo, foram contabilizados 2.382 indivíduos pertencentes a 29 táxons, incluindo cinco marsupiais (Didelphidae; 1,39% dos indivíduos), quatro quirópteros (Molossidae, Phyllostomidae e Vespertilionidae; 0,25%) e 20 roedores (Cricetidae, Muridae, Caviidae e Echimyidae; 98,36%). Os roedores Akodon spp., Oligoryzomys sp. e Mus musculus foram os táxons mais comuns. A amostra inclui espécies com poucos registros para o sul do Brasil, como Bibimys sp., Calomys tener e Wilfredomys oenax. A riqueza de pequenos mamíferos obtida nessas amostras corrobora a utilidade e importância da análise de egagropilos de aves de rapina. Ainda assim, são necessários estudos mais detalhados sobre a morfologia e identificação das espécies, como de Akodon e Oligoryzomys, considerando-se a natureza fragmentária do material nos egagropilos.

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The Pampa biogeographic province covers a mere 2% of the Brazilian territory (176,496 km²). However, it stands out as a complex and diverse ecosystem, although its mammal communities are still scarcely understood. Human activities are transforming the territory into a mosaic of agroecosystems, native and exotic forest fragments, and grasslands. Here we conducted the first investigation to determine the richness of small mammal assemblages in the region based on extensive analyses of owl pellets (Tyto furcata). Craniodental remains were studied from samples collected from 12 Semi-deciduous Seasonal Forest sites in the municipality of São Lourenço do Sul, State of Rio Grande do Sul, Southern Brazil. A total of 2,617 individuals belonging to 19 taxa were recorded, including 2 marsupials (Didelphidae; 0.42%), 2 chiropterans (Molossidae, Phyllostomidae; 0.12%), and 15 rodents (Cricetidae, Muridae, Caviidae; 99.46%). The rodent genera Oligoryzomys, Mus, Calomys, and Akodon were the most common taxa. Large samples also included poorly known taxa, such as the cricetids Bibimys, Juliomys (recording here its southernmost occurrence), Lundomys, and Wilfredomys. From a biogeographical point of view, the recorded assemblage embraces a mixture of Platan, Pampean, and Atlantic Forest elements, highlighting the role of the southernmost Brazilian hills as a wedge favoring the penetration of forest micromammals to higher latitudes. Our findings testify to the great diversity of the Pampa, but also point to a growing homogeneity and dominance of rodent species that are widespread in agroecosystems. Rapid inventories based on owl pellets emerge as a suitable, economic, non-invasive tool to document these community changes.