Why was "tantrum" trending last week?
composed of some but not all members descending from a common ancestor
Relating to a taxonomic group that includes some but not all of the descendants of a common ancestor. In the traditional taxonomy of vertebrates, where fish are a separate class from the classes of terrestrial vertebrates, the class of fish is paraphyletic, since the terrestrial vertebrates are descended from a type of fish. Compare monophyletic, polyphyletic.