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The cranial endoskeleton of Tiktaalik roseae


Among the morphological changes that occurred during the ‘fish-to-tetrapod’ transition was a marked reorganization of the cranial endoskeleton. Details of this transition, including the sequence of character acquisition, have not been evident from the fossil record. Here we describe the braincase, palatoquadrate and branchial skeleton of Tiktaalik roseae, the Late Devonian sarcopterygian fish most closely related to tetrapods. Although retaining a primitive configuration in many respects, the cranial endoskeleton of T. roseae shares derived features with tetrapods such as a large basal articulation and a flat, horizontally oriented entopterygoid. Other features in T. roseae, like the short, straight hyomandibula, show morphology intermediate between the condition observed in more primitive fish and that observed in tetrapods. The combination of characters in T. roseae helps to resolve the relative timing of modifications in the cranial endoskeleton. The sequence of modifications suggests changes in head mobility and intracranial kinesis that have ramifications for the origin of vertebrate terrestriality.

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Figure 1: Nunavut Fossil Vertebrate Collection (NUFV) 110, skull of Tiktaalik roseae in ventral view.
Figure 2: Reconstruction of the braincase and palatoquadrate of Tiktaalik roseae in lateral view.
Figure 3: Reconstruction of the otic-occipital and caudal end of the ethmosphenoid of Tiktaalik roseae in ventral view based primarily on NUFV 110.
Figure 4: NUFV 110, left hyomandibula of Tiktaalik roseae.
Figure 5: Cladogram of select tetrapodomorphs.
Figure 6: Schematic diagram of ventral branchial elements of Tiktaalik roseae in dorsal view.

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  1. Vorobyeva, E. I. Observations on two rhipidistian fishes from the Upper Devonian of Lode, Latvia. Zool. J. Linn. Soc. 70, 191–201 (1980)

    Article  Google Scholar 

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

    Google Scholar 

  3. Schultze, H.-P. & Arsenault, M. The panderichthyid fish Elpistostege: A close relative of tetrapods? Palaeontology 28, 292–309 (1985)

    Google Scholar 

  4. Schultze, H.-P. in Devonian Fishes and Plants of Miguasha, Quebec, Canada (eds Schultze, H.-P. & Cloutier, R.) 316–327 (Verlag Dr. Friedrich Pfeil, 1996)

    Google Scholar 

  5. Daeschler, E. B., Shubin, N. H. & Jenkins, F. A. A Devonian tetrapod-like fish and the evolution of the tetrapod body plan. Nature 440, 757–763 (2006)

    Article  ADS  CAS  Google Scholar 

  6. Shubin, N. H., Daeschler, E. B. & Jenkins, F. A. The pectoral fin of Tiktaalik roseae and the origin of the tetrapod limb. Nature 440, 764–771 (2006)

    Article  ADS  CAS  Google Scholar 

  7. Ahlberg, P. E. & Johanson, Z. Osteolepiforms and the ancestry of tetrapods. Nature 395, 792–794 (1998)

    Article  ADS  Google Scholar 

  8. Long, J. A., Young, G. C., Holland, T., Senden, T. J. & Fitzgerald, E. M. G. An exceptional Devonian fish from Australia sheds light on tetrapod origins. Nature 444, 199–202 (2006)

    Article  ADS  CAS  Google Scholar 

  9. Ahlberg, P. E., Clack, J. A., Lukševičs, E., Blom, H. & Zupinš, I. Ventastega curonica and the origin of tetrapod morphology. Nature 453, 1199–1204 (2008)

    Article  ADS  CAS  Google Scholar 

  10. Ahlberg, P. E., Clack, J. A. & Lukševičs, E. Rapid braincase evolution between Panderichthys and the earliest tetrapods. Nature 381, 61–64 (1996)

    Article  ADS  CAS  Google Scholar 

  11. Clack, J. A. The Origin of Tetrapods. in Amphibian Biology Vol. 4 (eds Heatwole, H. & Carroll, R.) 979–1029 (Surrey Beatty and Sons, 2000)

    Google Scholar 

  12. Clack, J. A. Acanthostega gunnari, a Devonian tetrapod from Greenland; the snout, palate, and ventral parts of the braincase, with a discussion of their significance. Meddelelser Grønland Geosci. 31, 1–24 (1994)

    Google Scholar 

  13. Clack, J. A. The neurocranium of Acanthostega gunnari Jarvik and the evolution of the otic region in tetrapods. Zool. J. Linn. Soc. 122, 61–97 (1998)

    Article  Google Scholar 

  14. Brazeau, M. D. & Ahlberg, P. E. Tetrapod-like middle ear architecture in a Devonian fish. Nature 439, 318–321 (2006)

    Article  ADS  CAS  Google Scholar 

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

    Google Scholar 

  16. Smithson, T. R. & Thomson, K. S. The hyomandibular of Eusthenopteron foordi Whiteaves (Pisces: Crossopterygii) and the early evolution of the tetrapod stapes. Zool. J. Linn. Soc. 74, 93–103 (1982)

    Article  Google Scholar 

  17. Romer, A. S. The braincase of the Carboniferous crossopterygian Megalichthys nitidus . Bull. Mus. Comp. Zool. 82, 1–73 (1937)

    Google Scholar 

  18. Romer, A. S. Notes on the crossopterygian hyomandibular and braincase. J. Morphol. 69, 141–180 (1941)

    Article  Google Scholar 

  19. Fox, R. C., Campbell, K. S. W., Barwick, R. E. & Long, J. A. A new osteolepiform from the Lower Carboniferous Raymond Formation, Drummond Basin, Queensland. Mem. Queensl. Mus. 38, 97–221 (1995)

    Google Scholar 

  20. Long, J. A., Barwick, R. E. & Campbell, K. S. W. Osteology and functional morphology of the osteolepiform fish Gogonasus andrewsae Long, 1985, from the Upper Devonian Gogo Formation, Western Australia. Rec. West. Aus. Mus. 53 (suppl.). 1–89 (1997)

    Google Scholar 

  21. Johanson, Z., Ahlberg, P. & Ritchie, A. The braincase and palate of the tetrapodomorph sarcopterygian Mandageria fairfaxi: morphological variability near the fish-tetrapod transition. Palaeontology 46, 271–293 (2003)

    Article  Google Scholar 

  22. Thomson, K. S. The endocranium and associated structures in the Middle Devonian rhipidistian fish Osteolepis . Proc. Linn. Soc. Lond. Zool. 176, 181–195 (1965)

    Article  Google Scholar 

  23. Lebedev, O. A. Morphology of a new osteolepidid fish from Russia. Bull. Mus. Natl. Hist. Nat. Paris 17, 287–341 (1995)

    Google Scholar 

  24. Johanson, Z. & Ahlberg, P. E. A new tristichopterid (Osteolepiformes: Sarcopterygii) from the Mandagery Sandstone (Late Devonian, Famennian) near Canowindra, NSW, Australia. Trans. R. Soc. Edinb. 88, 39–68 (1997)

    Article  Google Scholar 

  25. Coates, M. I. & Clack, J. Fish-like gills and breathing in the earliest known tetrapod. Nature 352, 234–236 (1991)

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  27. Clack, J. A. Discovery of the earliest-known tetrapod stapes. Nature 342, 425–427 (1989)

    Article  ADS  CAS  Google Scholar 

  28. Thomson, K. S. T. Mechanisms of intracranial kinetics in fossil rhipidistian fishes (Crosspoterygii) and their relatives. Zool. J. Linn. Soc. 46, 223–253 (1967)

    Article  Google Scholar 

  29. Carroll, R. L. in The Terrestrial Environment and the Origin of Land Vertebrates (ed. Panchen, A. L.) 293–317 (Academic, 1980)

    Google Scholar 

  30. Clack, J. A. Pattern and processes in the early evolution of the tetrapod ear. J. Neurobiol. 53, 251–264 (2002)

    Article  Google Scholar 

  31. Clack, J. A. in The Evolutionary Biology of Hearing (eds Webster, D. B., Ray, R. R. & Popper, A. N.) 405–420 (Springer, 1996)

    Google Scholar 

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The illustrations are the work of K. Monoyios. Specimen preparation was performed by C. F. Mullison. This research was made possible by permits from the Nunavut Ministry of Culture, Languages, Elders and Youth, the Grise Fiord Hamlet and HTA, with logistical support from the Polar Continental Shelf Project and collections support from the Canadian Museum of Nature. M. Brazeau improved interpretation of P. rhombolepis and offered input. Assistance in the field (1999–2006) was provided by W. Amaral, B. Atagootak, J. Conrad, M. Davis, S. Gatesy, A. Gillis, B. Kilbourne, S. Madsen, K. Middleton, J. Miller, K. Monoyios, C. Schaff, M. Shapiro, R. Shearman and C. Sullivan. This research was supported by an anonymous donor, the Academy of Natural Sciences of Philadelphia, the Putnam Expeditionary Fund (Harvard University), the University of Chicago, the National Science Foundation, and the National Geographic Society Committee for Research and Exploration.

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Correspondence to Jason P. Downs or Neil H. Shubin.

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Downs, J., Daeschler, E., Jenkins, F. et al. The cranial endoskeleton of Tiktaalik roseae. Nature 455, 925–929 (2008).

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