paraphyletic

[păr′ə-fī-lĕtĭk]
  1. Relating to a taxonomic group that includes some but not all of the descendants of a common ancestor. In the traditional taxonomy of vertebrates, where fish are a separate class from the classes of terrestrial vertebrates, the class of fish is paraphyletic, since the terrestrial vertebrates are descended from a type of fish. Compare monophyletic polyphyletic.
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