clade

A grouping of organisms made on the basis of their presumed evolutionary history, rather than purely on shared features. Clades consist of a common ancestor and all its descendants. The class Aves (birds) is a clade, but the class Reptilia (reptiles) is not, since it does not include birds, which are descended from the dinosaurs, a kind of reptile. Many modern taxonomists prefer to use clades in classification, and not all clades correspond to traditional groups like classes, orders, and phyla.

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