EXCALIBOR - Empirical and experimental calibration of a clumped isotope (paleo)thermometer for bioapatites
Final Report Abstract
We have established the first detailed calibration of the clumped isotope thermometer for carbonate-bearing (bio)apatites in a temperature range from 7°-80°C. At a given temperature, there occurs no significant difference in the clumped isotopic compositions (D47) of dentin, enamel(oid) and synthetic carbonate-bearing apatite. The temperature dependence of D47 is indistinguishable from that of calcite made in the same lab. Moreover, we determined the temperature dependence of oxygen isotope fractionation between the structurally substituted carbonate group in apatite and water. The two calibrations were applied to determine the body temperature of C. megalodon and the oxygen isotopic composition (d18O) of the seawater this shark lived in. The inferred body temperature and seawater d18O are within the preferred habitat temperature range of the modern lamniform great white shark and the Miocene/Pliocene seawater d18O range, respectively. These results demonstrate that both calibrations can be successfully applied to fossil teeth enamel(oid) to reconstruct the body temperature of extinct vertebrates and the oxygen isotopic composition of the water/body fluid the teeth crystallized from.
Publications
- (2016) Slight pressure imbalances can affect accuracy and precision of dual inlet-based clumped isotope analysis. Isot. Environ. Health Stud. 52, 12-28
Fiebig J., Hofmann S., Niklas L., Luedecke T., Methner K. and Wacker U.
(See online at https://doi.org/10.1080/10256016.2015.1010531) - (2016). Clumped isotope thermometry of carbonate-bearing apatite: Revised sample pretreatment, acid digestion, and temperature calibration. Chem. Geol. 443, 97-110
Wacker, U., Rutz, T., Löffler, N., Conrad, A.C., Tütken, T., Böttcher, M.E., Fiebig, J.
(See online at https://doi.org/10.1016/j.chemgeo.2016.09.009)
