more-primitive characteristic that appeared in common ancestors.

anatomically similar structure inherited from a common ancestor.

reduced form of a functional structure that indicates shared ancestry.

structure that has the same function but different construction and was not inherited from a common ancestor.

organism's early pre-birth stage of development

study of the distribution of plants and animals on Earth

measure of a trait's relative contribution to the following generation.

morphological adaptations that allow organisms to blend into their surroundings

morphological adaptation in which one species evolves to resemble another species for protection or other advantages.