Inner ear development in cyclostomes and evolution of the vertebrate semicircular canals

  title={Inner ear development in cyclostomes and evolution of the vertebrate semicircular canals},
  author={Shinnosuke Higuchi and Fumiaki Sugahara and Juan Pascual-Anaya and Wataru Takagi and Yasuhiro Oisi and Shigeru Kuratani},
Jawed vertebrates have inner ears with three semicircular canals, the presence of which has been used as a key to understanding evolutionary relationships. Ostracoderms, the jawless stem gnathostomes, had only two canals and lacked the lateral canal1–3. Lampreys, which are modern cyclostomes, are generally thought to possess two semicircular canals whereas the hagfishes—which are also cyclostomes—have only a single canal, which used to be regarded as a more primitive trait1,4. However, recent… 

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