South Brazil pre-colonial sharks: Insights into biodiversity and species distributions

South Brazil's archaeological coastal sites (shellmounds and middens) show a diverse collection of shark faunal remains, some of which belong to species considered rare nowadays for the region. However, shark archaeological remains identification in this region has been historically insufficient and prone to mistakes. This study identified shark fauna and estimated body size (total length) present at two archaeological sites: Rio do Meio (1220-977 Cal B.P.) and Enseada II (4286-3783 Cal B.P.), located in Santa Catarina, South of Brazil. Here, 1600 teeth and 3588 vertebrae were analysed and identified. We showed higher historical shark species richness than previously reported for South Brazil in historical and archaeological studies. In total, we identified at least 15 species of sharks (11 species and four identifications at the genus level). The presence of juvenile shark remains adds to the evidence of pre-colonial fishing impacts in local shark populations. The consistent recovery of adults and juveniles of Carcharias taurus points to a possible nursery area on the mouth of Babitonga bay. The high teeth frequency (43%) of C. taurus suggests the South Brazil coastline was once home to abundant populations of this critically endangered species. Furthermore, we discuss the presence of rare species nowadays, suggesting a possible historical residency for adult populations of Carcharodon carcharias based on the presence of juveniles and young-of-the-year on archaeological sites. The occurrence of Negaprion brevirostris, a tropical species, might have been facilitated by ocean current variations.