bio

Paraphyly

A group consisting of a common ancestor and some - but not all - of its descendants. A paraphyletic group is a truncated limb: it omits a few descendant branches, so it is not a complete family. "Fish" is the classic case - it bundles nearly all descendants of one ancestor but leaves out the land-dwelling tetrapods, which also came from that ancestor. Modern systematics avoids paraphyletic groups because they reflect convenience, not ancestry.