Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Earliest known tetrapod braincase and the evolution of the stapes and fenestra ovalis


ACANTHOSTEGA gunnari, from the Upper Devonian (Famennian) of East Greenland, is the most primitive known tetrapod, and retains many fish-like characters1–4. I report here the discovery of further well preserved specimens that show the earliest known tetrapod braincase, and shed light on the history of the tetrapod ear region. The fenestra ovalis is shown to be derived directly from the vestibular fontanelle5,6, a hole in the sidewall of the braincase of fishes seen in their embryology and in primitive fossil fish adults. The hole is not a uniquely tetrapod character7,8. A specialized auditory fenestra ovalis may have evolved more than once among tetrapods. As in other tetrapods, the stapedial footplate of Acan-thostega fitted into the fenestra ovalis, but instead of being free to vibrate as part of an ear, was firmly held there, forming a major component of the braincase wall. It was the only component linking the otic capsule to the palate. Though the stapes may have carried muscles operating a spiracular valve, the new material suggests that it was not a mobile component of the skull as previously suggested4. The stapes, spatially replacing parts of the fish brain-case including the process carrying facets for the hyomandibular articulation9, has a footplate which incorporates both heads of the sarcopterygian hyomandibula.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. Coates, M. I. & Clack, J. A. Nature 352, 234–236 (1991).

    ADS  Article  Google Scholar 

  2. Clack, J. A. & Coates, M. I. in Deciphering the Natural World and the Role of Collections and Museums (eds Hoch, E. & Brantsen, A. K.) 39–42 (Geological Museum Copenhagen, 1993).

    Google Scholar 

  3. Coates, M. I. & Clack, J. A. Nature 347, 66–69 (1990).

    ADS  Article  Google Scholar 

  4. Clack, J. Nature 342, 425–130 (1989).

    ADS  CAS  Article  Google Scholar 

  5. Jarvik, E. Basic Structure and Evolution of Vertebrates Vol. 1 (Academic, London, 1980).

    Google Scholar 

  6. Gardiner, B. G. Bull. Br. Mus. (nat. Hist.) Geol. 37, 173–428 (1984).

    Google Scholar 

  7. Gaffney, E. S. Bull. Carn. Mus. nat. Hist. 13, 92–105 (1979).

    Google Scholar 

  8. Panchen, A. L. & Smithson, T. R. Biol. Rev. 62, 341–438 (1987).

    Article  Google Scholar 

  9. Smithson, T. R. & Thomson, K. S. Zool. J. Linn. Soc. 74, 93–103 (1982).

    Article  Google Scholar 

  10. de Beer, G. R. The Development of the Vertebrate Skull (Clarendon, Oxford, 1937).

    Google Scholar 

  11. Lombard, R. E. & Bolt J. R. Biol. J. Linn. Soc. 11, 19–76 (1979).

    Article  Google Scholar 

  12. Clack, J. A. in The Evolutionary Biology of Hearing (eds Webster, D. B., Fay, R. R. & Popper, A. N.) 405–420 (Springer, New York, 1992).

    Book  Google Scholar 

  13. Beaumont, E. I. Phil. Trans. R. Soc. B280, 29–101 (1977).

    Article  Google Scholar 

  14. Smithson, T. R. Zool. J. Linn. Soc. 76, 29–90 (1982).

    Article  Google Scholar 

  15. Clack, J. A. & Holmes, R. B. Palaeontology 31, 85–107 (1988).

    Google Scholar 

  16. Romer, A. S. & Witter, R. V. J. Geol. 50, 925–960 (1942).

    ADS  Article  Google Scholar 

  17. Panchen, A. L. & Smithson, T. R. in The Phytogeny and Classification of Tetrapods, Vol. 1: Amphibians, Reptiles and Birds (ed. Benton, M. J.) 1–32 (Clarendon, Oxford, 1988).

    Google Scholar 

  18. Jarvik, E. Kungl. svenksa vetensk. acad. handl. 5, 1–104 (1954).

    Google Scholar 

  19. Moy-Thomas, J. A. & Miles, R. S. Palaeozoic Fishes (Chapman and Hall, London, 1971).

    Book  Google Scholar 

  20. Vorobyeva, E. I. & Schultze, H.-P. in Origins of the Higher Tetrapod Groups (eds Trueb, L. & Schultze, H.-P.) 68–109 (Cornell Univ. Press, New York, 1991).

    Google Scholar 

  21. Eaton, T. J. J. Wash. Acad. Sci. 29, 109–117 (1939).

    Google Scholar 

  22. Huxley, T. H. Proc. zool. Soc. Lond. 1876, 24–59 (1876)

    Google Scholar 

  23. Goodrich, E. S. Studies on the Structure and Development of Vertebrates 1958 edn (Dover, New York, 1930).

    Book  Google Scholar 

  24. Wake, M. H. Hyman's Comparative Vertebrate Anatomy 3rd edn (Univ. Chicago Press, Chicago, 1979).

    Google Scholar 

  25. Carroll, R. L. in The Terrestrial Environment and the Origin of Land Vertebrates (ed. A. L. Panchen) 293–318 (Academic, London, 1980).

    Google Scholar 

  26. Allis, E. P. J. Anat. 56, 189–294 (1922).

    CAS  PubMed  PubMed Central  Google Scholar 

Download references

Author information

Authors and Affiliations


Rights and permissions

Reprints and Permissions

About this article

Cite this article

Clack, J. Earliest known tetrapod braincase and the evolution of the stapes and fenestra ovalis. Nature 369, 392–394 (1994).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing