The micro from mega: Dental calculus description and the first record of fossilized oral bacteria from an extinct proboscidean

Abstract

ObjectiveThis study explores the chemical composition and surface aspects of fossilized dental calculus from the South American Quaternary proboscidean Notiomastodon platensis and the first record of fossilized oral bacteria from extinct megafauna. MaterialsBlocks of dental calculus removed from the third molar of five specimens of Notiomastodon platensis collected from Brazil, Argentina, and Ecuador. MethodsWe analyzed five samples of dental calculus by SEM and SEM-EDS, following a rigid protocol to avoid bacterial contamination. ResultsThe dental calculus surface is homogeneous, porous, with various crystals, and composed mainly by oxygen and calcium. One sample revealed a well-preserved mineralized biofilm, with several rods and cocci bacteria. ConclusionsThis is the first fossilized record of oral bacterial communities associated with extinct proboscideans. SignificanceThis record confirms the parasitism between oral bacteria and Notiomastodon platensis and will enable the study of paleogenomic aspects of oral microbiota of proboscideans. LimitationsFossilization conditions of proboscidean teeth with dental calculus are variable among specimens. Although rare, the preservation of oral bacteria is expected because of the oral biofilm composition.