Teeth of past and present elephants: Microstructure and composition of enamel in fossilized proboscidean molars and implications for diagenesis

Enamel as hardest biological tissue remains unaltered for millions of years and is therefore an excellent archive for studies on paleodiet, paleoecology, paleoclimate, paleoenvironment, biomechanical and evolutionary studies. However, diagenetic alterations can influence such interpretations and therefore we analyzed the microstructure and composition (elemental and stable isotopic) of fossil and extant proboscidean teeth to study the extent of diagenesis in them. We report for the first time on the enamel microstructure data of the Indian elephantiformes Anancus, Stegodon, Elephas and Palaeoloxodon besides analyzing Gomphotherium and Deinotherium from new formations. Furthermore, we compare their microstructure with those of the primitive African taxa of Moeritherium and Palaeomastodon. Our results from depth-related elemental composition and oxygen isotope ratios of enamel phosphate and carbonate indicate no or only negligible modification. There is also a lack of age-dependency of these minor alterations within the fossils collected from Siwaliks of the Himalayan Foreland Basin. Overall, our study indicates that diagenesis has not played any significant role on the samples studied here and are therefore well suited for chemical and paleontological studies and proxy for paleoclimate and paleoenvironment reconstruction.