鸟类骨盆发育中的祖先恐龙特征
作者：Christopher T. Griffin, João F. Botelho, Michael Hanson et al.
链接：
https://www.nature.com/articles/s41586-022-04982-w
摘要：
我们使用胚胎学成像技术在三个维度上检查鸟类盆腔组织的形态发生，与化石记录进行直接比较。许多恐龙祖先的特征（例如，前向耻骨、短髂骨和耻骨）在鸟类的早期形态发生中短暂存在，并通过反映特征获得的系统发育序列的产前发育序列过渡后达到典型的“活鸟”形态。
我们定量地证明了鸟类骨盆个体发生与非鸟类恐龙到鸟类的转变相似，并为骨盆内表型协方差提供了证据。鸟类胚胎中存在的祖先状态可能源于这种保守的协变关系。
总之，我们的数据提供了证据，证明鸟类骨盆的早期发育是通过末端附加的机制进化的，即新的非形形状态被添加到发育序列的末端，导致该序列中更早的祖先特征状态的表达。
Abstract：
We used embryological imaging techniques to examine the morphogenesis of avian pelvic tissues in three dimensions, allowing direct comparison with the fossil record. Many ancestral dinosaurian features (for example, a forward-facing pubis, short ilium and pubic ‘boot’) are transiently present in the early morphogenesis of birds and arrive at their typical ‘avian’ form after transitioning through a prenatal developmental sequence that mirrors the phylogenetic sequence of character acquisition. We demonstrate quantitatively that avian pelvic ontogeny parallels the non-avian dinosaur-to-bird transition and provide evidence for phenotypic covariance within the pelvis that is conserved across Archosauria. The presence of ancestral states in avian embryos may stem from this conserved covariant relationship. In sum, our data provide evidence that the avian pelvis, whose early development has been little studied, evolved through terminal addition—a mechanism whereby new apomorphic states are added to the end of a developmental sequence, resulting in expression8,11 of ancestral character states earlier in that sequence.
