Dentin hardness differences across various mammalian taxa. (2nd December 2021)

• Record Type: Journal Article
• Authors: Geissler, Elise; McGraw, W. Scott; Daegling, David J.
• Is Part Of: Journal of morphology. Volume 283:Number 1(2022)
• Page Start: 109
• Page End: 122
• Publication Date: 2021-12-02
• Subjects: biomechanics -- dentin -- Knoop hardness test -- microhardness; Morphology -- Periodicals; Physiology -- Periodicals; Anatomy -- Periodicals; 571.3
• DOI: 10.1002/jmor.21430
• Languages: English
• ISSNs: 0362-2525

Abstract

Abstract: Differences in dentin microstructure have been used as a tool for dietary reconstruction; however, the extent that diet is associated with this aspect of dental morphology has yet to be empirically tested. We conducted microhardness tests of mammalian dentin sections, hypothesizing that species with adaptations to particularly hard diets would have softer dentin, owing to a higher proportion of soft intertubular dentin. Species adapted to abrasive diets, in contrast, should have harder dentin, resulting from a higher proportion of hypermineralized peritubular dentin. We examined molar dentin hardness in ten mammalian taxa with durophagous diets, abrasive diets, and a comparative "control" group of mechanical generalists. Samples included six primate taxa and four non‐primate species representing various dietary regimes. Our results reveal significant variation among taxa in overall hardness, but the data do not distinguish between hard and abrasive diets. Several taxa with generalized (i.e., mechanically diverse) diets resemble each other in exhibiting large variance in hardness measurements and comparably soft dentin. The high variation in these species appears to be either a functional signal supporting the niche variation hypothesis or indicate the absence of sustained unidirectional selective pressure. A possible phylogenetic signal of dentin hardness in the data also holds promise for future systematic investigations. Abstract : The sources of variation in mammalian dentin microstructure are not known. We examined the microhardness of dentin across various mammalian species, including six primate taxa, to better understand the potential effects of diet and phylogeny. Differences in sampled taxa fall largely along phylogenetic lines; however, some dietary generalists resemble each other in having softer dentin with greater variance, presumably reflecting their broader dietary niches.