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

ABSTRACT

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, Brazil). The studied material includes 2,683 craniomandibular remains totalizing about 20 sigmodontine species. 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 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.

KEYWORDS:

• Archaeological remains
• climate
• environment
• owl pellets
• Rio Grande do Sul

Acknowledgments

We thank A. Dias and the MARSUL for the material loan, P.C. Simões-Lopes and M.E. Graipel for the access of the UFSC collection, A. Christoff for the access of the MCNU collection, T. Trigo for the access of the MCN-M collection, A. Dias for the access of the UFRGS collection, S. Klamt for the access of the UNISC collection, S. Althoff for the acess of the CZFURB collection and J.A. Oliveira for the access of the specimens of Wilfredomys oenax of the MN collection. We also want to thank the Central Laboratory of Electronic Microscopy of UFSC for the MEV photos, JP. Saldanha for the preparation of Figure 1; P. Teta, E. González and Historical Biology editors for their useful suggestions; and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), the Agencia Nacional de Promoción Científica y Tecnológica and the Consejo Superior de Investigaciones Científicas de Cooperación Internacional for the financial support.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Additional information

Funding

This work was financially supported by the CNPq under Grant 133086/2017-8 (NS) and Grant 444508/2014-7 (PH), Agencia Nacional de Promoción Científica y Tecnológica under Grant PICT 2014–1039 (UFJP); and Consejo Superior de Investigaciones Científicas de Cooperación Internacional under Grant i-COOPB-20287 (FJF).