All early vertebrate embryos develop tails and gill slits, and therefore this type of anatomical evidence supports common ancestry
Explanation:
Embryology is a discipline that studies the structural/anatomical features and development of embryos. Embryos are a fundamental piece of evidence to support common ancestry among vertebrates because there are homologous structural features that can only be observed during the first stages of vertebrate development. For example, all vertebrate embryos (e.g., fish, chicken and human embryos), develop tails and gill slits during their first stages of embryo development. In consequence, embryology provides evidence for evolution of vertebrates.
