A new Late Miocene hystricognath rodent assemblage (Caviidae, Dinomyidae, and Neoepiblemidae) from northern Brazil and its biostratigraphic relevance

ABSTRACT

The Neogene strata of the Solimões Formation (northern Brazil) have revealed an astonishing diversity of extinct caviomorph rodents. The main exposures of this formation are found along the Juruá, Acre, and Purus rivers, and some road cuts in the State of Acre. In this paper, we reported a new locality containing a rodent assemblage. The outcrop (Coqueiro locality) is located in the Envira River, central region of State of Acre, Brazil. During fieldwork in 2010 and 2019, several isolated cheek teeth and bones of mammals were recovered in conglomeratic levels from this locality. Here, we described specimens assigned to Cardiatherium sp. (Caviidae: Hydrochoerinae), Potamarchus sp. and cf. Pseudopotamarchus (Dinomyidae: Potamarchinae), and Neoepiblema sp. (Neoepiblemidae). The locality is not yet dated by radiometric methods but based on the biostratigraphic information of the taxa here reported, we suggest that the fossil-bearing levels of this locality were deposited during the Late Miocene.

KEYWORDS:

• Solimões Formation
• Caviomorpha
• biodiversity
• fossil record
• Neogene
• South America

Acknowledgments

Universidade Federal do Acre, Seção de Paleontologia of the Museu de Ciências Naturais, SEMA-RS, and Centro de Apoio à Pesquisa Paleontológica da Universidade Federal de Santa Maria for the infrastructure. María Encarnación Pérez and anonymous reviewer for valuable comments that significantly improved the final version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

E.F. was financed by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (Protax/CNPq 140639/2021-7). A.M.R. is supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (Protax/CNPq441626/2020-3; PQ310023/2021-1), Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul 21/2551-0002030-0, CNPq/MCTI/CONFAP-FAPS 21/2551-0000781-8 (CNPq/MCTI/CONFAP-FAPS 21/2551-0000781-8). L.K. is supported Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq 422568/2018-0; 309414/2019-9), and Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (21/2551-0002030-0).