Physicochemical analysis of Catonyx cuvieri (Mammalia, Xenarthra) remains from the Pleistocene of Paraguay

Abstract

The fossil-diagenetic characteristics, such as mineralogical aspects present in the ribs of Catonyx cuvieri (Lund, 1839) (Mammalia, Xenarthra), were analyzed in this work. These analyzed remains come from the Risso Cave, San Lazaro's District, Concepción Department, Paraguay. The vibrational response was studied using Raman and Fourier transform infrared (FTIR) and the mineralogy and elemental compositions were examined using multiple characterizations techniques. The main functional groups belong to the mineral part of the bone, and specific functional groups were associated with organic components. The characterization indicated that material was composed of apatites and the original mineral structure was affected by partial ionic substitutions, probably due to the interaction of the fossil with the environment. A Gaussian deconvolution model (GM) was used to identify the individual overlapping bands in the regions of interest in the spectra. A diagenesis pathway for the fossil involved the inclusion of calcium carbonate on the surface of the bone due to the accumulation of moisture, which allowed the recrystallization of hydroxyapatite and the precipitation of calcite in the pores and silicates of the bone. It’s worth mentioning that this work is the first in the ground sloths C. cuvieri in South America. In addition, the material here constitutes the most complete fossil record of a member of the Pleistocene megafaunal of Paraguay.