Evolution of the ribcage morphology in the linage toward birds : a study based on functional morphology and developmental biology

点击翻译按钮获取中文摘要

I studied the ribcage development in the extant archosaurs(alligator and chicken), to understand the homologies between the avian-specific ribcage and the ancestral ribcage. In the alligator embryo, the three-segmented rib pattern develops in concordance with the positions of nerves and muscles, suggesting that the difference between this three-segmented and the avian two-segmented patterns is not due to the difference in ossification levels. Analyses on fossils of the Mesozoic theropods demonstrated that the acquisition of the avian two-segmented rib pattern was essential to the respiratory evolution in the lineage toward birds.