A '''clade'''<ref>(from [[Ancient Greek]] ''{{Polytonic|κλάδος}}'', ''klados'', "branch")</ref> is a group that consistsconsisting of 1)an all the descendants of a common ancestororganism and 2)all thatits ancestordescendants. For example, birds, dinosaurs, crocodiles, and their extinct relatives form a clade.<ref>[http://evolution.berkeley.edu/evolibrary/glossary/glossary_popup.php?word=clade Glossary entry "clade"] Understanding Evolution. 2010. University of California Museum of Paleontology.</ref> In the terms of [[systematics|biological systematics]], a clade is a single "branch" on the "[[Tree of life (science)|tree of life]]".<ref>{{cite journal | last=Dupuis | first=Claude | year=1984 | title=Willi Hennig's impact on taxonomic thought | journal=Annual Review of Ecology and Systematics | volume=15 | pages=1–24 | issn=0066-4162}}</ref> The idea that such a "natural group" of organisms should be grouped together and given a [[Taxonomy|taxonomic]] name is central to [[biological classification]]. In [[cladistics]] (which takes its name from the term), clades are the only acceptable units.
The term was coined by [[England|English]] biologist [[Julian Huxley]].
