摘要
Dietary preferences of extant reptiles can be directly observed, whereas diet reconstruction of extinct species typically relies on morphological or dental features. More specific information about the ingested diet is contained in the chemistry of hard tissues. Stable isotopes of calcium and strontium show systematic fractionations between diet and skeletal bioapatite, which is applied for diet and trophic-level reconstructions of extant and extinct vertebrate species. Here, we present the first comprehensive analysis of stable calcium and strontium isotopes of bones and teeth from 28 extant reptiles, including lepidosaurs and archosaurs (crocodilians) with distinct herbivorous to faunivorous feeding behaviour, establishing a dietary reference frame. Both calcium and strontium isotopes exhibit systematic offsets between dietary groups, with insectivores having the highest, herbivores intermediate and carnivores the lowest calcium and strontium isotope values. Although the isotopic trophic-level effect is similar to mammals, the absolute calcium isotope values in reptiles are more positive in each diet category. Combining isotopic data with dental microwear texture analysis enables a refined understanding of reptile feeding ecology and the identification of durophagous diets. This toolbox opens new possibilities for improved dietary reconstructions of extinct taxa, such as dinosaurs and other non-mammalian species in the fossil record.
摘要译文
现存爬行动物的食物偏好可以直接观察到，而灭绝物种的食物重建通常依赖于形态或牙齿特征。 关于摄入饮食的更具体信息包含在硬组织化学中。 钙和锶的稳定同位素显示膳食和骨骼生物磷灰石之间的系统分馏，其应用于现存和灭绝脊椎动物物种的膳食和营养水平重建。 在此，我们首次对28种现存爬行动物的骨骼和牙齿的稳定钙和锶同位素进行了全面分析，包括鳞龙和弓龙（鳄鱼属），这些爬行动物具有不同的食草性到食肉性摄食行为，建立了膳食参考框架。 钙和锶同位素在膳食组之间显示出系统性偏移，食虫类钙和锶同位素值最高，草食类居中，食肉类最低。 虽然同位素营养水平的影响与哺乳动物相似，但爬行动物的绝对钙同位素值在每种食物类别中更积极。 结合同位素数据与牙科微磨损质地分析，可以更好地理解爬行动物摄食生态学，并识别食硬食性食物。 这个工具箱为改善已灭绝的分类群（如恐龙和化石记录中的其他非哺乳动物物种）的膳食重建开辟了新的可能性。
Michael Weber; Katrin Weber; Daniela E. Winkler;Thomas Tütken. Calcium and strontium isotopes in extant diapsid reptiles reflect dietary tendencies—a reference frame for diet reconstructions in the fossil record[J]. Proceedings of the Royal Society of London B: Biological Sciences, 2025,292(2038)