Tropical Fossil Caviomorph Rodents from the Southwestern Brazilian Amazonia in the Context of the South American Faunas: Systematics, Biochronology, and Paleobiogeography

Author(s)

Kerber, Leonardo ; Negri, Francisco Ricardo ; Ribeiro, Ana Maria ; Nasif, Norma ; Souza-Filho, Jonas Pereira ; Ferigolo, Jorge

• Document type: Journal article
• Source: JOURNAL OF MAMMALIAN EVOLUTION; v. 24, n. 1, p. 14-pg., 2017-03-01.

Abstract

The fossil-bearing stratigraphic sections of the Solimes Formation (southwestern Brazilian Amazonia) are exposed mainly along the Jurua, Purus, and Acre rivers, and in road cuts. These deposits have provided fossils of the four main lineages of Caviomorpha - Cavioidea, Erethizontoidea, Octodontoidea, and Chinchilloidea, contributing to the understanding on the evolution of tropical Neogene rodents. Herein, our knowledge about fossil rodents from this region is reviewed. New specimens are recorded, including taxa mentioned for this region for the first time, such as basal cavioids, Dolichotinae, Caviodon (Hydrochoeridae), and Drytomomys (Dinomyidae). Unfortunately, the deposits have no absolute ages, and based on palynological data and the biochronology of several taxa (mainly mammals), the encompassed fauna has been constrained to the late Miocene. However, some rodent lineages recorded here seem to be more related to older faunas, from the middle Miocene and Paleogene. Regarding the biogeographic and paleoenvironmental affinities, most of the Neogene rodents from the Acre region show more similarities to those from the Entre Rios, Argentina, and Urumaco, Venezuela, where wet environments were present during Neogene times. An increase in prospecting along southwestern Amazonian rivers looking for rodents (among other vertebrates) associated with methods to better constrain the ages of these faunal assemblages will contribute to a better understanding of the evolution of the tropical rodents as well as the stratigraphy and age of that portion of the basin. (AU)

• FAPESP's process: 11/14080-0 - Cretaceous and Tertiary (Paleogene/Neogene) Squamates (Reptilia, Lepidosauria) from the Bauru, Aiuruoca and Acre basins: systematics, evolution and palaeoenvironments
• Grantee: Annie Schmaltz Hsiou
• Support Opportunities: Research Grants - Young Investigators Grants