Pushing the limits of bioapatite clumped isotope analysis: resolving endo- from ectothermy in mosasaurs

我们最近证明，现代脊椎动物牙齿的聚集同位素组成完全受温度控制。因此，生物磷灰石聚集同位素温度计可能有潜力解决已灭绝脊椎动物的内外温关系。然而，这种新的温度计应用于中小型灭绝脊椎动物目前受到限制，因为这种分析需要相对较大的样本量（250- 1250 mg）的未改变的牙釉质（oid）。在这里，我们要求资金，以显着减少这一样本量的15-20倍。然后，我们的目标是将这种新的分析设置的牙齿沧龙和同期沉积的含碳酸盐相，以澄清这些海洋爬行动物是否是内温动物或外温动物。它们在上白垩纪的世界海洋中的广泛丰度允许调查体温是否随古纬度（40°N至65°S）和身体大小而变化，或者与这些参数无关。沧龙的牙齿和同期沉积的碳酸盐和鱼的牙齿都将通过一系列最先进的分析技术进行深入筛选，以确定这些样本的哪些部分受到成岩作用的影响。两者合计，这些系统的调查是基本的探索的潜力的生物磷灰石块同位素温度计重建的小型和中型灭绝脊椎动物的热生理。

We have recently demonstrated that the clumped isotopic composition of teeth of modern vertebrates is exclusively controlled by temperature. As such, the bioapatite clumped isotope thermometer may have the potential to resolve endo- from ectothermy in extinct vertebrates. However, an application of this new thermometer to small and medium sized extinct vertebrates is currently limited by the relatively large sample size (250-1250mg) of unaltered tooth enamel(oid) required for such analysis. Here, we request funding to significantly reduce this sample size by a factor of 15-20. We then aim at applying this new analytical setup to teeth from mosasaurs and contemporaneously deposited carbonate-bearing phases to clarify whether these marine reptiles were endo- or ectotherms. Their widespread abundance in the world’s ocean of the Upper Cretaceous allows to investigate if body temperatures varies with paleolatitude (40°N to 65°S) and body size or occurs decoupled from these parameters. Both mosasaur teeth and contemporaneously deposited carbonates and fish teeth will be intensively screened by an array of state-of-the-art analytical techniques to identify which parts of these samples were affected by diagenesis. Taken together, these systematic investigations are fundamental for an exploration of the potential of the bioapatite clumped isotope thermometer for the reconstruction of thermophysiology of small and medium sized extinct vertebrates.