Noteworthy sigmodontine diversity (Rodentia: Cricetidae: Sigmodontinae) in southern Brazil as an indication of environmental change during the Holocene

NARLA SHANNAY STUTZ; PATRÍCIA HADLER; JORGE JOSÉ CHEREM; FERNANDO JULIAN FERNÁNDEZ; ANA MARIA RIBEIRO; ULYSES PARDIÑAS

Historical Biology

Taylor & Francis

Año: 2020 vol. 32 p. 649 - 670

0891-2963

We describe a new sigmodontine fossil sequence ranging from 8,800±40 to 3,730±60 years BP retrieved from the archaeological site RS-S-327:Sangão (Rio Grande do Sul, southern Brazil). The studied material includes 2,683 craniomandibular remains totalizing about 20 species of sigmodontine rodents. The assemblage encompasses a variety of taxa associated to both open and forest environments. Among the former, we recorded species today disappeared in southern Brazil such as the rare ?giant? rats Gyldenstolpia and Kunsia, but also the coney rat Reithrodon and the akodontine Necromys obscurus. Conversely, an important assemblage of sylvan species, including the genera Delomys, Oecomys, and Wilfredomys, reflects forested environments. Several of the recorded sigmodontines, such as Deltamys or Nectomys, constitute first mentions for the southern Brazil Quaternary. One of the most remarkable features of the studied sequence is its noteworthy specific richness, probably due to a combination of local environmental heterogeneity in a regional tendency of changing climatic conditions. The evidence of Sangão plus the previously studied samples from Garivaldino and Pilger sites exposes dramatic faunal changes during the Holocene in southern Brazil. In this context, the impoverishment of recent sigmodontine assemblages seems a natural result from the progressive disappearance of extensive open environments since Middle Holocene.