polyphyletic taxon
Definition | Source | References |
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A group composed of a collection of organisms in which the most recent common ancestor of all the included organisms is not included, usually because the common ancestor lacks the characteristics of the group. Polyphyletic taxa are considered unnatural, and usually are reclassified once they are discovered to be polyphyletic. |
Global assessment (1st work programme) | University of California, 2009 |