noun au·tap·o·mor·phy \ȯ-ˈta-pə-ˌmȯr-fē\

Definition of autapomorphy



biological taxonomy

  1. :  a specialized character or trait that is unique to a monophyletic taxonomic group … An eversible penis is a synapomorphy that unites lizards and snakes in a common monophyletic group, the Squamata, but is an autapomorphy of the Squamata within a larger monophyletic assemblage. — Robert L. Carroll, Patterns and Processes in Vertebrate Evolution, 1997 These species share key traits as autapomorphies of their clade—and since these traits help to construct the relevant environment, sufficient similarity becomes, in part, an active construction of related organisms, not only a happenstance of common externalities. — Stephen Jay Gould, The Structure of Evolutionary Theory, 2002


\ȯ-ˌta-pə-ˈmȯr-fik\ play less commonly


\ȯ-ˈta-pə-ˌmȯrf\ play adjective These features are not known for any Jurassic and Cretaceous mammals and are autapomorphic for this new mammalian lineage. — Zhe-Xi Luo and John R. Wible, Science, 1 Apr. 2005


\ȯ-ˌta-pə-ˈmȯr-fəs\ play adjective The Chondrichthyes are a monophyletic clade and are principally distinguished on the basis of two unique autapomorphous character sets. — Eileen D. Grogan and Richard Lund, in Biology of Sharks and their Relatives, 2004

Love words? You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Join MWU now and get access to America’s largest dictionary, with:

  • 300,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

Origin and Etymology of autapomorphy

autapomorph (borrowed from German, from aut- aut- + apomorph “apomorphic”) + 2-y — more at apomorphy

First Known Use: 1959

Seen and Heard

What made you want to look up autapomorphy? Please tell us where you read or heard it (including the quote, if possible).


a rounded knoll or a ridge of ice

Get Word of the Day daily email!