Existing temperature estimates for the early Paleozoic have large errors and/or are likely affected by strong diagenetic biases. This uncertainty compromises efforts to use conditions of the early Paleozoic as a natural climate experiment for times when controlling variables (e.g., pCO2, solar luminosity, terrestrial vegetation, paleogeography) differed markedly from the later portions of the Phanerozoic up to the modern. To begin to address this problem, PIs will measure d18O values of up to 1000 early to mid-Paleozoic conodont samples. Because phosphate oxygen, especially in material with relatively high crystallinity like the lamellar hydroxyfluorapatite of conodont elements, is diagenetically more robust than carbonate oxygen, d18O measurements of bioapatite has great potential to advance knowledge of Paleozoic temperatures. Analytical advances have reduced the required sample size and increased sample throughput without compromising accuracy or precision. In addition, for this proposal PIs have access to thousands of samples that are already processed. Coupled with our analytical capabilities, this sample base provides an unparalleled opportunity to efficiently conduct a d18O survey from a range of taxa representing different regions, different times, and different states of preservation. Samples analyzed will come primarily from the University of Missouri conodont collection but will also include specimens from the large collections spanning the Late Ordovician housed at Ohio State University and from those spanning the Cambrian-Ordovician boundary housed at Missouri State University. With these samples PIs will 1) document temporal patterns in conodont d18O across ~160 million years at multiple sites with better than million-year average resolution, 2) compare d18O values with visual (cathodoluminescence, color alteration index, reflected light, and SEM) and geochemical (ICP-MS) observations of preservation to test empirically how robust conodont d18O values are, and 3) compare d18O values of various conodont taxa within multiple samples to search for consistent interspecies differences.
