Paraphyly

Paraphyly is a term used in biology to describe a group of organisms that includes some, but not all, descendants of a common ancestor. In simpler terms, it means that a group is incomplete because it excludes certain related species. For example, reptiles can be considered paraphyletic if we group them together but leave out birds, even though birds evolved from reptiles. This contrasts with monophyly, where a group includes all descendants of a common ancestor, and polyphyly, which groups organisms based on similar traits but without regard for their common ancestry.