Data from: Rates of morphological evolution are heterogeneous in Early Cretaceous birds

The Early Cretaceous is a critical interval in the early history of birds. Exceptional fossils indicate that important evolutionary novelties such as a pygostyle and a keeled sternum had already arisen in Early Cretaceous taxa, bridging much of the morphological gap between Archaeopteryx and crown birds. However, detailed features of basal bird evolution remain obscure because of both the small sample of fossil taxa previously considered and a lack of quantitative studies assessing rates of morphological evolution. Here we apply a recently available phylogenetic method and associated sensitivity tests to a large data matrix of morphological characters to quantify rates of morphological evolution in Early Cretaceous birds. Our results reveal that although rates were highly heterogeneous between different Early Cretaceous avian lineages, consistent patterns of significantly high or low rates were harder to pinpoint. Nevertheless, evidence for accelerated evolutionary rates is strongest at the point when Ornithuromorpha (the clade comprises all extant birds and descendants from their most recent common ancestors) split from Enantiornithes (a diverse clade that went extinct at the end-Cretaceous), consistent with the hypothesis that this key split opened up new niches and ultimately led to greater diversity for these two dominant clades of Mesozoic birds.

Usage Notes
phylogenetic methods and sensitivity testsComplete data used in Wang and Graeme's paper, including following files: data matrix of Mesozoic birds, age of the terminal taxa, most parsimonious trees, code in R analysis, and the complete results of the sensitive tests.Dryad.rar

早白垩纪是鸟类早期历史中的一个关键时期。卓越的化石记录表明，诸如尾综骨和肋骨板等重要进化创新已在早白垩纪的物种中产生，填补了始祖鸟与真鸟之间的形态学鸿沟的大部分。然而，由于先前考虑的化石物种样本量小以及缺乏评估形态学进化速率的定量研究，基础鸟类的进化细节仍显晦涩。在本研究中，我们运用了一种近期可用的系统发育方法及其相关的敏感性测试，对大量形态学特征的数据矩阵进行量化，以评估早白垩纪鸟类的形态学进化速率。我们的结果表明，尽管不同早白垩纪鸟类谱系之间的进化速率存在高度异质性，但显著高或低的速率模式难以确切指出。尽管如此，加速的进化速率的证据在鸟纲（该类群包括所有现存鸟类及其最近共同祖先的后裔）从反鸟纲（一个在白垩纪末期灭绝的多样类群）分离时最为明显，这与这一关键分离打开了新的生态位并最终导致中生代鸟类两大优势类群多样性增加的假说相一致。

使用说明

系统发育方法和敏感性测试

Wang 和 Graeme 论文中使用的完整数据，包括以下文件：中生代鸟类的数据矩阵、终端物种的年龄、最简约树、R 分析代码以及敏感性测试的完整结果。
Dryad.rar