后口动物咽鳃裂的起源和演化

Origin and evolution of pharyngeal gill slits in Deuterostomia

咽鳃裂构造是定义后口动物亚界的一个关键性状。寒武纪古虫动物门由于体侧的五对咽鳃裂及一系列的原始性状被论证为后口动物谱系最理想的一个根底类群。古虫动物咽鳃裂被证实与后口动物咽鳃裂同源,其原始功能主要是排出咽内海水。古虫动物门的出现标志着后口动物咽鳃裂的起源。咽鳃裂的诞生引发了动物界摄食及呼吸等基础新陈代谢的革命,并为后口动物的崛起奠定了基础。

Pharyngeal gill slits are a key synapomorphy for defining the Deuterostomia. The Cambrian vetulicolians have been demonstrated to be the most ideal stem-group deuterostomes, based on their possession of a series of gill slits combined with primitive characters. The vetulicolian gill slits are justified to be homologous to pharyngeal gill slits of deuterostomes, with their primitive function as ventilation openings to expel seawater from the pharyngeal cavity. The emergence of the phylum Vetulicolia during the Cambrian explosion of life signals the birth of the pharyngeal gill slits in deuterostomes, which triggered a revolution in efficiency of basal metabolism （not least feeding and respiration） in the kingdom Animalia and paved the way for the subsequent rise of the Deuterostomia.