Paraphyletic Taxa

paraphyletic taxon
 
The Paraphyletic taxon is a group of organisms in which the most recent common ancestor of all those organisms and some, but not all, of that ancestor's descendents are included.  Paraphyletic taxa are recognised in Linnean and evolutionary systematics but not in cladistics.

Illustration: the Class Reptilia gave rise to mammals and birds, but neither mammals nor birds are included under Reptilia.

Examples:  Invertebrates, Amphibia, Reptilia, Dinosauria (excluding birds), Gymnosperma, etc.
 
 

graphic (top) from UCMP
 
 
 

Polyphyletic taxon
Paraphyletic taxon
Monophyletic taxon
 
 
 
 
 
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page history

page uploaded 13 November 1998
modified 28 November
and again 18 December