The latitudinal biodiversity gradient (LBG), the increase in biodiversity from the poles to the equator, is one of the most widely recognized global macroecological patterns, yet its deep time evolution and drivers remain uncertain. The Late Triassic (237–201 Ma), a critical interval for the early evolution and radiation of modern tetrapod groups (e.g. crocodylomorphs, dinosaurs, mammaliamorphs), offers a unique opportunity to explore the palaeolatitudinal patterns of tetrapod diversity since it is extensively sampled spatially when compared with other pre‐Cenozoic intervals, particularly at lower palaeolatitudes. Here, we explore palaeolatitudinal patterns of Late Triassic tetrapod diversity by applying sampling standardization to comprehensive occurrence data from the Paleobiology Database (PBDB). We then use palaeoclimatic model simulations to explore the palaeoclimatic ranges occupied by major tetrapod groups, allowing insight into the influence of palaeoclimate on the palaeolatitudinal distribution of these groups. Our results show that Late Triassic tetrapods generally do not conform to a modern‐type LBG; instead, sampling‐standardized species richness is highest at mid‐palaeolatitudes. In contrast, the richness of pseudosuchians (crocodylians and their relatives) is highest at the palaeoequator, a pattern that is retained throughout their subsequent evolutionary history. Pseudosuchians generally occupied a more restricted range of palaeoclimatic conditions than other tetrapod groups, a condition analogous to modern day reptilian ectotherms, while avemetatarsalians (the archosaur group containing dinosaurs and pterosaurs) exhibit comparatively wider ranges, which is more similar to modern endotherms, such as birds and mammals, suggesting important implications for the evolution of thermal physiology in dinosaurs.

中文翻译：

---

晚三叠世四足动物多样性纬度变化的气候驱动因素

纬度生物多样性梯度（LBG），即从两极到赤道的生物多样性增加，是最广泛认可的全球宏观生态学模式之一，但其深度演化和动因仍不确定。三叠纪晚期（237-201 Ma）是现代四足动物群（如鳄鱼，恐龙，哺乳动物）的早期进化和辐射的关键区间，因为它在空间上被广泛采样，因此为探索四足动物多样性的古纬度格局提供了独特的机会。与其他新生代前期相比，尤其是在古近纪时期。在这里，我们通过将采样标准化应用于古生物学数据库（PBDB）的综合发生数据，探索了晚三叠纪四足动物多样性的古纬度格局。然后，我们使用古气候模型模拟来探索主要四足动物群所占据的古气候范围，从而洞悉古气候对这些群的古纬度分布的影响。我们的结果表明，三叠纪晚期的四足动物通常不符合现代型的LBG。取而代之的是，采样标准化的物种丰富度是在中古高原最高的。相反，在古赤道，伪鳄（鳄鱼和他们的亲戚）的财富最高，这种模式在他们随后的进化史中一直保持着。与其他四足动物类相比，伪类动物通常所处的古气候条件范围更受限制，该条件类似于现代爬虫类等温线，