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

碳酸盐中13 C-18 O键（成团同位素，测量为D47）的丰度是碳酸盐结晶温度的直接测量，与母体流体的同位素组成无关。因此，碳酸盐的成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，也可以分析其聚集的同位素组成。最近有人提出，生物磷灰石中同位素凝聚的温度依赖性很高，可以从牙齿分析中分辨出恐龙是外生生物还是吸热生物。我们已经成功地建立了生物磷灰石中碳酸盐和碳酸盐的凝聚同位素分析技术。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太明显，比以前假设的。我们请求资助，以便能够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（生物）磷灰石的磷酸消化产生的CO2的D47。为了这个目的，我们将分析D47的釉质/釉质和牙本质从已知的体温类群的牙齿和含碳酸盐无机沉淀hydroxyapatites.Our结果将是必不可少的评估是否D47分析化石生物磷灰石有可能提供体温的灭绝脊椎动物。

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.