Data from: The impact of phylogenetic dating method on interpreting trait evolution: a case study of Cretaceous–Palaeogene eutherian body-size evolution

The fossil record of the earliest Cenozoic contains the first large-bodied placental mammals. Several evolutionary models have been invoked to explain the transition from small to large body sizes, but methods for determining evolutionary mode of trait change depend on input from tree topology and divergence dates. Different dating methods may therefore affect inference of evolutionary model. Here, we fit models of body mass evolution onto dated phylogenies of Cretaceous and Palaeogene mammals, comparing the effect of dating method on interpretation of evolutionary model. Among traditional palaeontological dating approaches, an Ornstein–Uhlenbeck model with high alpha parameters is recovered as best-fitting when minimum-age dating is used, while branch-sharing methods are highly sensitive to topology. Release or release–radiate models are preferred when Bayesian fossilized birth–death method is used, but when using stochastic cal3 dating of trees, a model of increased evolutionary rate without a release in constraint at the Cretaceous–Palaeogene boundary has highest support. These results demonstrate unambiguously that choice of dating method is critical for interpretation of continuous trait evolution, and that care must therefore be taken to consider these effects in macroevolutionary studies.

新生代最早期的化石记录中，收录了首批体型庞大的有胎盘类哺乳动物（placental mammals）。学界已提出多种演化模型以解释体型从小型到大型的转变，但确定性状变化演化模式的方法，依赖于系统发育树拓扑结构（tree topology）与分化时间的输入数据。因此，不同的定年方法可能会影响演化模型的推断。本研究将体型质量演化模型拟合至白垩纪与古近纪哺乳动物的定年系统发育树中，对比不同定年方法对演化模型解读的影响。在传统古生物定年方法中，当使用最小年龄定年法（minimum-age dating）时，带有高α参数的奥恩斯坦-乌伦贝克模型（Ornstein–Uhlenbeck model）被恢复为最优拟合模型，而分支共享定年法（branch-sharing methods）对拓扑结构具有高度敏感性。当采用贝叶斯化石出生-死亡定年法（Bayesian fossilized birth–death method）时，更倾向于选择释放模型或释放-辐射模型；而当使用系统发育树的随机cal3定年法（stochastic cal3 dating）时，进化速率提升但未在白垩纪-古近纪界线（Cretaceous–Palaeogene boundary）处发生约束释放的模型获得最高支持度。本研究结果明确证实，定年方法的选择对于连续性状演化的解读至关重要，因此在宏观演化研究中，必须审慎考量此类定年方法带来的影响。