title: Electron spin resonance dating of megafauna from Lagoa dos Porcos, Piauí, Brazil.
abstract: Excavations performed at Lagoa dos Porcos site revealed a vast amount of extinct mammal fossil remains, becoming one of the richest palaeontological occurrences in the Serra da Capivara National Park region, a UNESCO World Heritage. Although anatomic and taxonomic aspects of extinct Quaternary mammals are relatively well known, chronologic information for deposits is rare. In this context, electron spin resonance (ESR) dating of megafauna samples provides important information for establishing a chronological background. This work presents the ESR dating of two teeth, one of Gomphotheriidae and other of Toxodontinae. Dose-response curves of each sample were constructed using spectra acquired with a JEOL FA-200 X-Band spectrometer resulting in equivalent dose (De) of 220 ± 40 Gy and 39 ± 2 Gy for Toxodontinae and Gomphotheriidae tooth, respectively. The conversion of De in age was made using ROSY ESR dating software resulting in 26 ± 4 and 22 ± 3 ka. These results place Lagoa dos Porcos fossil assemblage within the Late Pleistocene. These dates overlap with a period of abrupt increase in rainfall in northeast Brazil, and it is possible that this environmental change is related to the formation of this deposit.
authors.affiliation: Universidade Sagrado Coração-USC-Bauru, São Paulo, Brazil Departamento de Física, Universidade de São Paulo, FFCLRP, Ribeirão Preto, São Paulo, Brazil Present address: Rua Irmã Arminda 10-50, 17.011-160, Bauru, SP, Brazil angelamitie@gmail.com.
authors.forename: Angela
authors.initials: A
authors.lastname: Kinoshita
authors.affiliation: Fundação Museu do Homem Americano, São Raimundo Nonato, Piauí, Brazil.
authors.forename: Elver
authors.initials: E
authors.lastname: Mayer
authors.affiliation: Fundação Museu do Homem Americano, São Raimundo Nonato, Piauí, Brazil.
authors.forename: Vinícius
authors.initials: V
authors.lastname: Ribau Mendes
authors.affiliation: Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN, São Paulo, SP, Brazil.
authors.forename: Ana Maria G
authors.initials: AM
authors.lastname: Figueiredo
authors.affiliation: Departamento de Física, Universidade de São Paulo, FFCLRP, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Oswaldo
authors.initials: O
authors.lastname: Baffa
mesh_terms: D000366:Age Determination by Teeth; D000818:Animals; D001106:Archaeology; D001938:Brazil; D003743:Dental Enamel / Q000737:chemistry* / Q000528:radiation effects; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D005580:Fossils; D008322:Mammals; D010163:Paleontology; D011829:Radiation Dosage; D055110:Radiometric Dating / Q000379:methods*