EXCALIBOR - Empirical and experimental calibration of a clumped isotope (paleo)thermometer for bioapatites

碳酸盐中13C-18O键的丰度（块状同位素，测量为D47）是碳酸盐结晶温度的直接测量，与母流体的同位素组成无关。因此，碳酸盐的团块同位素分析已成为重建过去海洋和陆地温度的新工具。生物成因磷灰石通常含有<10%的碳酸盐，也可以分析其块状同位素组成。最近有人提出，生物磷灰石中同位素聚集的温度依赖性足够高，可以从牙齿分析中分辨恐龙是外生生物还是吸热生物。我们成功地建立了碳酸盐和生物磷灰石内部碳酸盐的团块同位素分析技术。我们的第一个结果表明，生物磷灰石的D47的温度依赖性可能不像以前假设的那么明显。我们请求资助，以完成我们的生物磷灰石T - D47校准，并研究生物磷灰石的组成和动力学是否会影响磷酸消化（生物）磷灰石产生的二氧化碳的D47。为此，我们将从已知体温的分类群的牙齿和含碳酸盐的无机沉淀羟基磷灰石中分析牙釉质/类釉质和牙本质的D47。我们的结果对于评估生物磷灰石化石的D47分析是否有可能提供灭绝脊椎动物的体温至关重要。

The abundance of 13C-18O bondings (clumped isotopes, measured as D47) in carbonates is a direct measure of carbonate crystallization temperature, independent of the isotopic composition of the parental fluid. Clumped isotope analysis of carbonates, therefore, has become a new tool to reconstruct past marine and terrestrial temperatures. Biogenic apatites usually contain <10% carbonate that can be analyzed for its clumped isotopic composition, too. It has been suggested very recently that the temperature dependence of isotopic clumping in bioapatites is sufficiently high to resolve from analysis of teeth whether dinosaurs were ecto- or endothermic organisms.We have successfully established the technique for clumped isotope analysis of carbonates and carbonate inside bioapatites. Our first results indicate that the temperature dependence of D47 of bioapatite might be less pronounced than previously assumed. We request funding to be able to complete our bioapatite T - D47 calibration for bioapatites and to study whether bioapatite composition and kinetics may affect D47 of CO2 resulting from phosphoric acid digestion of (bio)apatites. For this purpose, we will analyze D47 of enamel/enameloid and dentin from teeth of taxa with known body temperatures and from carbonate-bearing inorganically precipitated hydroxylapatites.Our results will be essential for evaluating whether D47 analyses of fossil bioapatites have the potential to deliver body temperatures of extinct vertebrates.