Final answer:
Embryology provides evidence of relatedness between groups of organisms. Embryonic traits that do not appear in the adult form are common in divergent groups. For example, all vertebrate embryos, including humans, exhibit gill slits and tails during early development, which disappear in the adult form of terrestrial species but are maintained in aquatic species.
Step-by-step explanation:
Embryology, the study of the development of the anatomy of an organism to its adult form, provides evidence of relatedness between divergent groups of organisms. Structures that are absent in some groups often appear in their embryonic forms and disappear when they reach the adult or juvenile form. For example, all vertebrate embryos, including humans, exhibit gill slits and tails at some point in their early development. These disappear in the adults of terrestrial groups but are maintained in adult forms of aquatic groups such as fish and some amphibians. Great ape embryos, including humans, have a tail structure during their development that is lost by the time of birth.