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Osteolepiforms and the ancestry of tetrapods


Fossil discoveries1,2,3,4,5,6,7 and improved phylogenies3,4,5,7 have greatly improved our understanding of the origin of tetrapods, making it possible to reconstruct sequences of character change leading to tetrapod morphologies5,7 and to tentatively identify the genetic basis for some of these changes8,9. However, progress has centred on the upper part of the Tetrapodomorpha5 which is occupied by Devonian tetrapods such as Acanthostega1,2,5 and Ichthyostega1. Few advances have been made in improving our understanding of the lower, ‘fish’ part of the group, beyond establishing Elpistostegalia, Osteolepiformes and Rhizodontida as progressively more primitive constituents10,11,12,13. It has not been convincingly confirmed or disproved that the Osteolepiformes, a diverse but structurally uniform group that is central to the debate about tetrapod origins14,15,16,17, is monophyletic relative to tetrapods (that is, a single side branch on the tetrapod lineage). The earliest steps of the fish–tetrapod transition have thus remained poorly resolved. Here we present the first detailed analysis of the lower part of the Tetrapodomorpha, based on 99 characters scored for 29 taxa. We show that both the Osteolepiformes as a whole and their constituent group Osteolepididae are paraphyletic to tetrapods (that is, each comprises a section of the tetrapod lineage with several side branches), and that their ‘uniting characters’ are attributes of the tetrapodomorph stem lineage. The supposedly discredited idea of osteolepiforms as tetrapod ancestors14,15,16,17 is, in effect, supported by our analysis. Tetrapod-like character complexes evolved three times in parallel within the Tetrapodomorpha.

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  1. 1

    Coates, M. I. & Clack J. A. Polydactyly in the earliest known tetrapod limbs. Nature 347, 66–69 (1990).

  2. 2

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

  3. 3

    Ahlberg, P. E. Elginerpeton pancheni and the earliest tetrapod clade. Nature 373, 420–425 (1995).

  4. 4

    Lebedev, O. A. & Coates, M. I. The postcranial skeleton of the Devonian tetrapod Tulerpeton curtum Lebedev. Zool. J. Linn. Soc. 114, 307–348 (1995).

  5. 5

    Coates, M. I. The Devonian tetrapod Acanthostega gunnari Jarvik: postcranial anatomy, basal tetrapod interrelationships and patterns of skeletal evolution. Trans. R. Soc. Edinb. Earth Sci. 87, 363–421 (1996).

  6. 6

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

  7. 7

    Ahlberg, P. E. Postcranial stem tetrapod remains from the Devonian of Scat Craig, Morayshire, Scotland. Zool. J. Linn. Soc. 122, 99–141 (1998).

  8. 8

    Shubin, N. The evolution of paired fins and the origin of tetrapod limbs. Evol. Biol. 28, 39–85 (1995).

  9. 9

    Shubin, N., Tabin, C. & Carroll, S. Fossils, genes and the evolution of animal limbs. Nature 388, 638–648 (1997).

  10. 10

    Schultze, H.-P. Dipnoans as sarcopterygians. J. Morphol. 1 (Suppl.), 39–74 (1986).

  11. 11

    Long, J. A. Anew rhizodontiform fish from the Early Carboniferous of Victoria, Australia, with remarks on the phylogenetic position of the group. J. Vert. Palaeontol. 9, 1–17 (1989).

  12. 12

    Cloutier, R. & Ahlberg, P. E. in Interrelationships of Fishes (eds Stiassny, M. L. J., Parenti, L. R. & Johnson, G. D.) 445–479 (Academic, San Diego, (1996).

  13. 13

    Johanson, Z. & Ahlberg, P. E. Acomplete primitive rhizodont from Australia. Nature 394, 569–572 (1998).

  14. 14

    Andrews, S. M. & Westoll, T. S. The postcranial skeleton of Eusthenopteron foordi Whiteaves. Trans. R. Soc. Edinb. 68, 207–329 (1970).

  15. 15

    Andrews, S. M. & Westoll, T. S. The postcranial skeleton of rhipidistian fishes excluding Eusthenopteron. Trans. R. Soc. Edinb. 68, 391–489 (1970).

  16. 16

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

  17. 17

    Rackoff, J. S. in The Terrestrial Environment and the Origin of Land Vertebrates (ed. Panchen, A. L.) 255–292 (Academic, London, (1980)).

  18. 18

    Rosen, D. E., Forey, P. L., Gardiner, B. G. & Patterson, C. Lungfishes, tetrapods, palaeontology, and plesiomorphy. Bull. Am. Mus. Nat. Hist. 167, 159–276 (1981).

  19. 19

    Holmes, E. B. Are lungfishes the sister group of tetrapods? Biol. J. Linn. Soc. 25, 379–397 (1985).

  20. 20

    Panchen, A. L. & Smithson, T. S. Character diagnosis, fossils and the origin of tetrapods. Biol. Rev. Cambridge Phil. Soc. 62, 341–438 (1987).

  21. 21

    Young, G. C., Long, J. A. & Ritchie, A. Crossopterygian fishes from the Devonian of Antarctica: systematics, relationships and biogeographic significance. Rec. Austr. Mus. 14 (Suppl.), 1–77 (1992).

  22. 22

    Chang, M.-M. & Yu, X. Reexamination of the relationship of Middle Devonian osteolepids–fossil characters and their interpretations. Am. Mus. Novit. 3189, 1–20 (1997).

  23. 23

    Vorobyeva, E. I. 1977. Morphology and nature of evolution of crossopterygian fishes. Trudy Paleontol. Inst. 94, 1–239 (1977).

  24. 24

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

  25. 25

    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. Aust. Mus. 53 (Suppl.), 1–89 (1997).

  26. 26

    Andrews, S. M. Rhizodont crossopterygian fish from the Dinantian of Foulden, Berwickshire, Scotland, with a re-evaluation of this group. Trans. R. Soc. Edinb. Earth Sci. 76, 67–95 (1985).

  27. 27

    Ahlberg, P. E. & Johanson, Z. Send tristichopterid (Sarcopterygii, Osteolepiformes) from the Upper Devonian of Canowindra, New South Wales, Australia, and phylogeny of the Tristichopteridae. J. Vert. Palaeontol. 17, 653–673 (1997).

  28. 28

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

  29. 29

    Johanson, Z. & Ahlberg, P. E. New tristichopterid (Osteolepiformes: Sarcopterygii) from the Mandagery Sandstone (Famennian) near Canowindra, N. S. W., Australia. Trans. R. Soc. Edinb. Earth Sci. 88, 39–68 (1997).

  30. 30

    Chang, M.-M. & Min, Z. Anew Middle Devonian osteolepid from Qujing, Yunnan. Mem. Ass. Australasian Palaeontol. 15, 183–198 (1993).

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We thank the Australian Museum for their award of a Visiting Fellowship to P.E.A., E. Mark-Kurik for access to material of Thursius estonicus, J. Jeffery for information about rhizodonts and Academic Press for Figs 3a–c, 4a.

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Correspondence to Per E. Ahlberg.

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Figure 1: Previous osteolepiform phylogenies.
Figure 2: New phylogeny of the tetrapodomorph stem group (consensus of 9 trees, based on 99 characters scored for 29 taxa).
Figure 3: Ancestral characters for clade Elpistostegalia+Tetrapoda.
Figure 4: Parallel evolution in the tetrapod stem group, inferred from the phylogeny in Fig. 2.


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