22-1 The Whole Tooth and Nothing but the Tooth: How Isotopic Data from Multiple Tooth Components Can Be Used to Study Both Animal Biology & Behavior (Enamel) and Soil Hydrology (Dentine)

Session: Working Up an Apatite: Teeth as Paleo -Ecological and -Climatological Archives

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Carbon and oxygen isotope data from terrestrial vertebrate tooth enamel have long been used to infer dietary preferences (d13C) and sources of drinking water (d18O).  Depending on the taxa available for study, these data can in turn be used to recognize ecological niche partitioning and climatic conditions like relative humidity and mean annual precipitation.  This utility stems from enamels resistance to isotopic alteration, thus allowing primary biological information to be preserved.  In contrast, other components of teeth such as dentine are typically avoided when it comes to isotopic analysis as they are more prone to isotopic resetting in diagenetic/soil environments.  However, including isotopic data from altered dentine in any paleoecological study has the potential to greatly increase our understanding of the environments in which terrestrial vertebrates were living. In particular, d13C of dentine is influenced by the position of the water table which is in turn related to microtopography and to climate (e.g. evaporation minus precipitation).

As an illustration of how a combination of enamel and dentine data can be used to investigate the past, d18O and d13C from hadrosaurid dinosaur teeth collected from four vertebrate microsites in the late Cretaceous (Campanian) Kaiparowits Formation of Utah are presented.  Data from enamel indicate there are two discrete populations of hadrosaurs, each eating plants with different average d13C and thus occupying different parts of the paleolandscape.  Carbon isotope data from tooth dentine suggest that parts of the landscapes with higher d13C are associated with seasonally high water tables (= poorly drained) while those with lower d13C are associated with overall lower water tables (=better drained).   This association stands in contrast to that expected for C3 plants, and points to a more complex system of carbon cycling than is typically assumed in terrestrial settings.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10147

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