A new rodent (Caviomorpha: Dinomyidae) from the upper Miocene of southwestern Brazilian Amazonia |
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Authors: | Leonardo Kerber Marcos César Bissaro Júnior Francisco R. Negri Jonas Pereira de Souza-Filho Edson Guilherme Annie Schmaltz Hsiou |
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Affiliation: | 1. CAPPA - Centro de Apoio à Pesquisa Paleontológica da Quarta Col?nia and Programa de Pós-Gradua??o em Biodiversidade Animal, Universidade Federal de Santa Maria, S?o Jo?o do Polêsine, Brazilleonardokerber@gmail.com;3. Laboratório de Paleontologia, FFCLRP, Universidade de S?o Paulo, Ribeir?o Preto, Brazil;4. Laboratório de Paleontologia, Campus Floresta, Universidade Federal do Acre, Cruzeiro do Sul, Brazil;5. Laboratório de Paleontologia, Universidade Federal do Acre, Rio Branco, Brazil |
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Abstract: | Recently, the fossil record of rodents from southwestern Brazilian Amazonia has been reviewed with regards to its diversity as well as its ecological relationships. In the reviews, the necessity to report new specimens collected with stratigraphic control was stated. Here, a new dinomyid specimen collected during a 2015 expedition to the Niterói locality, Acre River, is reported. The material is a fragment of skull with the right P4–M1 and the left P4–M2 preserved. The cheek teeth are protohypsodont, a characteristic employed to differentiate Potamarchinae dinomyids from the euhypsodont dinomyids Eumegamyinae and Tetrastylinae. The occlusal surface of the cheek teeth is composed of lophs with interruptions, showing little wear, which suggests that the specimen is not fully ontogenetically developed. The specimen has a unique combination of characters (protohypsodont and pentalophodont cheek teeth, with the leading edges of similar thickness to the trailing edges, and presence of a groove on the bottom of the infraorbital foramen) not present in other known dinomyids, which led us to erect a new taxon. The abundant and diverse fossil record of protohypsodont dinomyids suggests that an important radiative event may have occurred during the middle–late Miocene of northern South America. http://zoobank.org/urn:lsid:zoobank.org:pub:E082C3C6-47B6-4D83-9009-A64879AAFC7A http://www.zoobank.org/NomenclaturalActs/16235A7B-A261-445E-8DD4-940AB21DCB06 |
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Keywords: | Ontogeny Niterói locality Chinchilloidea Potamarchinae protohypsodont Neogene |
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