Paraphyly

Paraphyly is a term in cladistics. It means a group which does not include all its descendents. So Sauropsida without birds is paraphyletic, since birds are definitely descended from archosaurs, probably small theropod dinosaurs (origin of birds).

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Paraphyly is corrected to monophyly when the missing group(s) are included. So if birds are included in Sauropsida, the larger group is then monophyletic.

Traditional Linnaean classification is often paraphyletic. Many common terms, like "fish", are paraphyletic, but still very useful for everyday purposes.

Paraphyly Media

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  In this phylogenetic tree, the green group is paraphyletic; it is composed of a common ancestor (the lowest green vertical stem) and some of its descendants, but it excludes the blue group (a monophyletic group) which diverged from the green group.

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  Cladogram of the primates, showing a monophyly (the simians, in yellow), a paraphyly (the prosimians, in blue, including the red patch), and a polyphyly (the night-active primates, the lorises and the tarsiers, in red).

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  Wasps are paraphyletic, consisting of the clade Apocrita without ants and bees, which are not usually considered to be wasps; the sawflies ("Symphyta") too are paraphyletic, as the Apocrita are nested inside the Symphytan clades.

Related pages

• Polyphyly