The stable carbon isotope composition of the structural carbonate derived from animal bone hydroxylapatite (δ¹³C_B-HA) could record an animal’s diet. These records provide critical evidence for different paleontological disciplines, e.g., paleodiet analyses, and paleoclimate reconstructions. Compared to those of other body tissues, such as bone collagen or teeth enamel hydroxylapatite, δ¹³C_B-HA values record information on the whole diet of an animal in its last years. δ¹³C_B-HA can be applied to fossil animals of various body sizes. The δ¹³C analytical instruments available only require that prepared bone samples be approximately 2–5 mg for precise measurement, allowing δ¹³C_B-HA analysis to be feasible on most vertebrate fossils without destructive sampling, especially on small mammals or birds whose teeth are not large enough for sampling or are lost. Moreover, δ¹³C_B-HA can be used from different times or under less than ideal burial environments. For fossils dating back to Devonian or buried in hot and humid regions, dietary information has been completely lost in bone collagen during post-depositional processes but still remained in the δ¹³C_B-HA values because hydroxylapatite is less influenced by diagenetic effects after deposition. In addition, systematic methods such as X-ray diffraction and Fourier transform infrared spectroscopy have been developed to qualitatively or semiquantitatively assess the influence of diagenesis on bone hydroxylapatite to ensure the credibility of the δ¹³C_B-HA values. With the above merits, δ¹³C_B-HA analysis is therefore becoming an increasingly important method in paleodiet-related research. Currently, applications of the δ¹³C_B-HA method on fossil animals are primarily focused on two aspects, namely, paleodietary reconstruction of fossil animals with uncertain diets and paleoenvironmental reconstruction based on the δ¹³C_B-HA values of fossil herbivores. The published researches, combined with our new results from early birds, demonstrate the considerable significance of the δ¹³C_B-HA method in paleontological and paleoenvironmental research. Notably, the δ¹³C_B-HA-based paleodietary analysis of early vertebrates, especially the large number of small birds or mammals discovered in the past decades would be an important work in the near future.

来源于动物骨羟基磷灰石（δ ¹³ C _B-HA）的结构碳酸盐的稳定碳同位素组成可以记录动物的饮食。这些记录为不同的古生物学学科提供了重要证据，例如古饮食分析和古气候重建。与其他身体组织（如骨胶原或牙釉质羟基磷灰石）相比，δ ¹³ C _B-HA值记录了动物最后几年整个饮食的信息。δ ¹³ C _B-HA可应用于各种体型的动物化石。δ ¹³可用的 C 分析仪器仅要求制备的骨骼样本约为 2-5 mg 以进行精确测量，从而可以对大多数脊椎动物化石进行 δ ¹³ C _B-HA分析而无需进行破坏性采样，尤其是对牙齿不大的小型哺乳动物或鸟类足够采样或丢失。此外，δ ¹³ C _B-HA可以在不同时间或在不太理想的埋葬环境下使用。对于可追溯到泥盆纪或埋藏在炎热潮湿地区的化石，饮食信息在沉积后过程中完全丢失在骨胶原中，但仍保留在 δ ¹³ C _{B-HA 中}值，因为羟基磷灰石在沉积后受成岩作用的影响较小。此外，还开发了X射线衍射和傅里叶变换红外光谱等系统方法来定性或半定量地评估成岩作用对骨羟基磷灰石的影响，以确保δ ¹³ C _B-HA值的可信度。凭借上述优点，δ ¹³ C _B-HA分析因此成为古饮食相关研究中越来越重要的方法。目前，δ ¹³ C _{B-HA的应用}化石动物的方法主要集中在两个方面，即饮食不确定的化石动物的古饮食重建和基于化石食草动物的δ ¹³ C _B-HA值的古环境重建。已发表的研究，结合我们早期鸟类的新结果，证明了 δ ¹³ C _B-HA方法在古生物学和古环境研究中的重要意义。值得注意的是，基于δ ¹³ C _B-HA的早期脊椎动物，特别是过去几十年发现的大量小型鸟类或哺乳动物的古饮食分析将是近期的一项重要工作。