Microstructure and chemical composition of fossil mammalian teeth

Abstract

Sectioned Cretaceous mammalian teeth were studied by light microscopy and SEM equipment with an electron microprobe. Structures resembling odontoblast processes were found. Their S/Fe ratio was similar to that of rat odontoblast processes, but the amounts of these elements were far higher than in processes of recent teeth. It was concluded that they consisted of pyrite, but their reaction with mercurochrome indicated presence of proteins with SH groups. Fluorescence microscopy indicated traces of collagen in the dentin. In the fossil enamel and dentin the Ca/P ratio was similar to that of recent teeth. Two samples of fossil teeth were analyzed for Pb, Cd, Zn, and Cu content by atomic absorption spectrophotometry. The levels of the latter two elements were normal, whereas that of Cd and especially that of Pb were higher than in laboratory rats. The probability that original protein fractions exist and that the different elements were those of the living animals is discussed.

Proteins in Art, Archaeology, and Paleontology: From Detection to Identification

“…The staining of proteins in fossils and archeological samples has been described since the early 1980s. , For example, mercurochrome was used on fossil teeth (transversal and longitudinal planes obtained using a wire string saw or abrasive paper) embedded in an epoxy resin (the stain reacts with sulfhydryl and disulfide groups of proteins). , Studies were performed using fluorescence microscopy analysis, and the compound exhibited an orange fluorescence (excitation wavelength 470 nm, emission wavelength 500–530 nm). Staining of fossil teeth was most pronounced near the pulp cavity, showing the presence of proteins in the dentin .…”

“…The staining of proteins in fossils and archeological samples has been described since the early 1980s. , For example, mercurochrome was used on fossil teeth (transversal and longitudinal planes obtained using a wire string saw or abrasive paper) embedded in an epoxy resin (the stain reacts with sulfhydryl and disulfide groups of proteins). , Studies were performed using fluorescence microscopy analysis, and the compound exhibited an orange fluorescence (excitation wavelength 470 nm, emission wavelength 500–530 nm). Staining of fossil teeth was most pronounced near the pulp cavity, showing the presence of proteins in the dentin . Colorimetric tests based on the use of ninhydrin (detailed previously) or OPA were also applied to detect the presence of proteins on prehistoric tools.…”

“…Staining of fossil teeth was most pronounced near the pulp cavity, showing the presence of proteins in the dentin. 26 Colorimetric tests based on the use of ninhydrin 27 (detailed previously) or OPA 27 were also applied to detect the presence of proteins on prehistoric tools. In the presence of βmercaptoethanol, OPA reacts with primary amine groups of proteins to form a blue colored fluorescent product (the unbound dye is nonfluorescent) (excitation wavelength 340 nm, emission wavelength 455 nm).…”