Dear Student, Embryology is the study of embryos in order to gain knowledge about the evolutionary relationships of various organisms. All vertebrates at their embryonic stage look very similar that shows that they all share common ancestry and link. Like notochord and gills clefts appear in every vertebrate at their embryonic stage.
The similarities in embryonic development reinforce the idea of evolution from common ancestors. The sequence of embryonic development in different vertebrates shows striking similarities. Notochord and gill clefts appear in the embryos of all vertebrates. Regards