A group composed of an ancestor and all of its descendants, no matter how much they may differ in for from the ancestral condition .
^Holtz, Dr. Thomas Jr.; Luis V. Rey (2007). Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages. Random House. ISBN9780375824197.Cite uses deprecated parameter |coauthor= (help)
This article is part of Project Glossary, a All Birds project that aims to write comprehensive articles on each term related to animals.