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The pterygoid and ectopterygoid in mammals

Summary

A dorsal pterygoid element and a ventral ectopterygoid element can be recognised during the development of monotremes, marsupials and eutherian mammals. Their homology with the elements so named in fossils ancestral to mammals can be established by positional evidence. In monotremes the elements remain distinct and show specialised features, including a hamular cartilage in the ectopterygoid of one specimen of Ornithorhynchus. In most higher mammals the pterygoid element is much reduced and is replaced anteriorly by the perpendicular plate of the palatine. Posteriorly the pterygoid element fuses with the ectopterygoid, in many cases before the onset of ossification. The hamular cartilage arises by chondrification within the ectopterygoid element and shows no sign of being a separate morphological entity, but must be regarded as a specialised feature associated with the architecture of the palatal musculature. There is a strong case for the value of recognising that the ‘pterygoid process’ of higher mammals includes both a pterygoid and an ectopterygoid moiety.

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References

  1. Alexander, R.McN.: The chordates. London: Cambridge University Press (1975)

    Google Scholar 

  2. Beer, G.R., de: The development of the skull of the shrew. Phil. Trans. Roy. Soc. B 217, 411–480 (1929)

    Google Scholar 

  3. Beer, G.R., de: The development of the vertebrate skull. Oxford University Press 1937

  4. Beer, G.R., de, Fell, W.A.: The development of the skull of Ornithorhynchus. Trans. Zool. Soc. Lond. 23, 1–42 (1936)

    Google Scholar 

  5. Bemmelen, J.F., van: Der Schädelbau der Monotremen. Denkschr. med.-naturw. Ges. Jena 3, 729–798 (1901)

    Google Scholar 

  6. Broom, R.: On the origin of mammals. Phil. Trans. Roy. Soc. B 206, 1–48 (1914)

    Google Scholar 

  7. Carter, G.S.: Structure and habit in vertebrate evolution. London: Sidgwick and Jackson 1967

    Google Scholar 

  8. Edgeworth, F.H.: The development of the cranial muscles of Tatusia and Manis. J. Anat. 57, 313–335 (1923)

    Google Scholar 

  9. Fawcett, E.: The early stages of the ossification of the pterygoid plates of the human sphenoid. J. Anat. 39, vi–viiP (1905)

    Google Scholar 

  10. Fourie, S.: The cranial morphology of Thrinaxodon liorhinus Seely. Ann. S. Afr. Mus. 65, 367–400 (1974)

    Google Scholar 

  11. Frazer, J.E.: Manual of embryology. London: Bailliere, Tindall and Cox 1931.

    Google Scholar 

  12. Fuchs, H.: Ueber das Pterygoid, Palatinum und Parasphenoid der Quadrupeden. Anat. Anz. 36, 33–95 (1910)

    Google Scholar 

  13. Gaupp, E.: Zur Entwicklungsgeschichte und vergleichenden Morphologie des Schädels von Echidna aculeata var typica. Denkschr. med.-naturw. Ges. Jena 8, 539–788 (1908)

    Google Scholar 

  14. Goodrich, E.S.: Studies on the structure and development of vertebrates. London: Macmillan 1930

    Google Scholar 

  15. Gray, H.: Gray's Anatomy (Warwick, R., Williams, P.L. eds.) (35th edition). Edingurgh: Longman 1973

    Google Scholar 

  16. Green, H.L.H.H.: A description of the egg tooth of Ornithorhynchus, together with some notes on the development of the palatine processes of the premaxilla. J. Anat. 64, 512–522 (1930)

    Google Scholar 

  17. Jollie, M.: Chordate morphology. New York: Reinhold 1962

    Google Scholar 

  18. Kampen, P.N., van: Parasphenoid und Basisphenoid der Säugetiere. Bijdr. Dierk. 22, 53–58 (1922)

    Google Scholar 

  19. Kesteven, H.L.: ‘The homology of the mammalian alisphenoid and of the echidna pterygoid’ J. Anat. 52, 223–238 (1918)

    Google Scholar 

  20. Kuhn, H.J.: Die Entwicklung und Morphologie des Schädels von Tachyglossus aculeatus. Abh. senckenb. naturforsch. Ges. 528, 1–224 (1971)

    Google Scholar 

  21. Lubosch, W.: Das Kiefergelenk der Edentaten und Marsupialier. Denkschr. med.-naturw.Ges.Jena 7, 1–38 (1907)

    Google Scholar 

  22. MacIntyre, G.T.: Foramen pseudovale and quasi-mammals. Evolution, Lancaster, Pa. 21, 834–841 (1967)

    Google Scholar 

  23. Parker, W.K.: The structure and development of the skull in mammalia (Part II Edentata, Part III, Insectivora). Phil. Trans. Roy. Soc. B 176, 1–275 (1885)

    Google Scholar 

  24. Parrington, F.R., Westoll, T.S.: The Evolution of mammalian palate. Proc Roy. Soc. B 230, 305–355 (1940)

    Google Scholar 

  25. Peter, K.: Über graphische Rekonstruktion in Schrägansicht. Z. wiss. Mikrosk. 39, 138–148 (1922)

    Google Scholar 

  26. Reinbach, W.: Zur Entwicklung des Primordial-craniums von Dasypus novemcinctus Linné. (I) Z. Morph. Anthrop. 44, 375–444; (II) Z. Morph. Anthrop. 45, 1–72 (1952)

    Google Scholar 

  27. Roux, G.H.: The cranial development of certain ethiopian insectivores and its bearing on the mutual affinities of the group. Acta Zoologica, Stockh. 28, 165–397 (1947)

    Google Scholar 

  28. Schneider, R.: Zur Entwicklung des Chondrocraniums der Gattung Bradypus. Morph. Jb. 96, 209–307 (1955)

    Google Scholar 

  29. Stadtmüller, F.: Kranium und Visceral-Skelett der Säugetiere. In: Bolk, Goppert, Kallius, Lubosch: Hdb. der vgl. Anat. d. Wirbeltiere 4, 839–1016 (1936)

    Google Scholar 

  30. Starck, D.: Le crâne des mammifères, in Grasse: Traité de Zoologie XVI (1), 405–549. Paris: Masson (1967)

    Google Scholar 

  31. Watson, D.M.S.: The monotreme skull: A contribution to mammalian morphogenesis. Phil. Trans. Roy. Soc. B 207, 311–374 (1916)

    Google Scholar 

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Presley, R., Steel, F.L.D. The pterygoid and ectopterygoid in mammals. Anat. Embryol. 154, 95–110 (1978). https://doi.org/10.1007/BF00317957

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Key words

  • Pterygoid
  • Ectopterygoid
  • Mammals
  • Cynodonts