Electron spin resonance dating of human teeth from Toca da Santa shelter of São Raimundo Nonato, Piauí, Brazil

Seventy C-14 dates were obtained going from 59,000 yBP to 5000 yBP at the actual soil [G.M. Santos, M.I., Bird, F. Parenti, L.K. Fifield, N. Guidon, P.A. Hausladen, Quaternary Sci. Rev. 22 (2003) 2303, [5]]. Beneath the date of 59,000 yBP it was found 1.5 m of archaeological layers, till the rock base. The cobbles that composed the structure of the hearths placed on top of the rock base were dated by thermoluminescence and the date of them is 100,000 yBP [H. Valladas, N. Mercier, M. Michab, J.L. Joron, J.L. Reiss, N. Guidon, N., Quaternary Sci. Rev. 22 (2003) 1257, [6]; H. Valladas, N. Mercier, M. Michab, J.L. Joron, J.L. Reyss, N. Guidon, Datações por Termoluminescência de Seixos de Quartzo Queimados da Toca do Boqueirão da Pedra Furada (Piauí, Nordeste do Brasil), Fumdhamentos III, 1 (2003) 35 (in Portuguese), [7]]. Thus chronological information is of paramount importance to contextualize and to understand the many questions regarding the human occupation of these sites [N. Guidon, A.M. Pessis, G. Martin, O Povoamento Pré-Histórico do Nordeste do Brasil, Proposta da: Fundação Museu do Homem Americano, e do Núcleo de Estudos Arqueológicos, da UFPE, CLIO ARQ, Recife 1 (6) (1990) 123, [8]]. To obtain more information Toca da Santa shelter, the nearest site to Toca do Gordo do Garrincho shelter, was also excavated and three incomplete skeletons with teeth were found at 80 cm depth. The teeth were cleaned and acid etched and enamel completely removed from dentine and crushed in particles smaller than 0.5 mm. Enamel was irradiated with a Co-60 source and measured with an ESR spectrometer (X-band) to obtain the signal versus dose curve. The archeological doses obtained by the fitting were (5.94 ± 0.07) Gy and (5.97 ± 0.08) Gy. Using the ROSY program an age of 5,700 ± 200 yBP was found for both teeth.