FOSSIL CRICETID RODENTS FROM THE QUATERNARY OF NORTHERN BRAZIL AND THEIR PALEOENVIRONMENTAL SIGNIFICANCE --- Preprint doi:10.5710/AMGH.14.11.2017.3094

Carolina Pires, Leonardo Avilla, Marcelo Weksler

Abstract


In this study, we record and describe fossil sigmodontine rodents from Gruta do Urso cave in the municipality of Aurora do Tocantins, Tocantins state, Northern Brazil. The sediments bearing fossil were deposited during a time span from 22,000 years before present (YBP) to 3,800 YBP, corresponding to the Late Pleistocene to Middle Holocene. The fossil specimens consist mostly of isolated molars and some fragments of maxillae and mandibles. We identified 12 sigmodontine taxa: Akodon sp. 1, Akodon sp. 2, Calomys sp., Holochilus sp., Kunsia tomentosus, Necromys lasiurus, Oecomys sp., Oligoryzomys sp. 1, Oligoryzomys cf. mattogrossae, Oxymycterus sp., Pseudoryzomys simplex, and Thalpomys lasiotis. This is the first fossil record for the group in Northern Brazil, and one of the largest assemblages of Pleistocene/Holocene sigmodontines registered in a single cave in the Neotropical region. Based on the diversity of sigmodontine rodents presented here, and on the associated fauna previously recorded at the same cave, we reconstruct the Late Pleistocene paleoenvironmental conditions of the region as an area dominated by open vegetation formation with gallery forest patches, similar to present conditions.

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