Análise dos remanescentes de Pinípedes (Carnivora - Otariidae) em sítios arqueológicos da planície costeira do Rio Grande do Sul, Brasil

Abstract

Pinnipeds are marine carnivores that emerged in the mid-Oligocene, around 65 million years ago. They occur in virtually every ocean in the world and have been interacting with human populations since prehistory in various regions of the globe. For the Brazilian coast eight species of pinnipeds have already been recorded, of which seven have been found on the coast of Rio Grande do Sul. Based on the analysis of bone remnants recovered at archaeological sites, it is suggested that the past records of pinnipeds on the coast of Brazil would be associated with Quaternary deposits. For the Rio Grande do Sul state coast there are few studies on osteology of pinnipeds, mostly diagnostic or sexual dimorphism studies base on skull samples of current species but there is very little information related to archaeological remnants of pinnipeds. In this context, it is still necessary the analyses of the species composition, abundance of individuals, occurrence and type of interaction of these species with prehistoric humans in the region. The present study was carried out in five archaeological sites on the north coast of Rio Grande do Sul (NCRS), between Xangri-la (29 ° 47'23.72 "S, 50 ° 02'1824" W) and Arroio do Sal 29 ° 27'0.27 "S, 49 ° 49'1.74" W), which were linked to the Sambaqui Tradition. The method of prospecting (excavation) was used in order to obatin several artificial horizontal levels, deepening vertically, forming successive artificial levels to assure the depth and origin of the faunistic remnants. The volume of material prospected at these five sites ranged from 0.30 m3 to ± 15.18 m3. In this study, six squares with faunal remnants of the five sites were selected for analysis, each differing in size and archaeological stratigraphic thickness. All the bone remains found in each square were collected in the excavated trenches and taken to the Archaeological Technical Reserve of the Instituto Anchietano de Pesquisas / Vale do Rio dos Sinos (IAP-UNISINOS). During the laboratory screening, only the remnants of pinnipeds were selected for this study, based on the comparison with skeletons of specimens of current species and the literature. As a result of taxonomic richness from the perspective of zooarchaeology, 159 remnants of pinnipeds were found as number of idenfied specimens (NISP) in the NCRS sites, totaling a minimum number of individuals (MNI) of 17. The RS-LN-19 site of Xangri-la presented the largest NISP, with 130 remnants only for the Otariidae Family, and with at least two identified species (Arctocephalus australis and Otaria flavescens). The analysis of the bone remnants of the genus Arctocephalus revealed the predominance of young individuals, and mainly adults of O. flavescens. This result in the past composition of the pinniped species found in the sambaquis in the RS coast suggests that they are the same that occur today, besides indicating that the ancient human populations already interacted with these animals. However, it is not ruled out that Antarctic and subantarctic antarctic have also occurred in the region in the past, since in some cases it was only possible to identify until the genus in the remnants analyzed. Finally, it is important to note that in 19.53% (n = 25) of the remaining bone remnants, anthropic manipulation marks were identified as cut (small oblique, transverse and subparallel incisions) and 5.46% (n = 7) blackened spots, possibly dut to burning. In this way, it is suggested that the ancient human populations of NCRS could use pinnipeds as an occasional food resource.