Letter | Published:

The axial skeleton of the Devonian tetrapod Ichthyostega

Nature volume 437, pages 137140 (01 September 2005) | Download Citation

Subjects

Abstract

Ichthyostega was the first Devonian tetrapod to be subject to a whole-body reconstruction1,2,3. It remains, together with Acanthostega4, one of only two Devonian tetrapods for which near-complete postcranial material is available. It is thus crucially important for our understanding of the earliest stages of tetrapod evolution and terrestrialization. Here we show a new reconstruction of Ichthyostega based on extensive re-examination of original material and augmented by recently collected specimens. Our reconstruction differs substantially from those previously published and reveals hitherto unrecognized regionalization in the vertebral column. Ichthyostega is the earliest vertebrate to show obvious adaptations for non-swimming locomotion. Uniquely among early tetrapods, the presacral vertebral column shows pronounced regionalization of neural arch morphology, suggesting that it was adapted for dorsoventral rather than lateral flexion.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    On the fish-like tail in the ichthyostegid stegocephalians. Meddelelser øm Grønland 114, 1–90 (1952)

  2. 2.

    The oldest tetrapods and their forerunners. Sci. Mon. 80, 141–154 (1955)

  3. 3.

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

  4. 4.

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

  5. 5.

    The Devonian tetrapod Ichthyostega. Fossils and Strata 40, 1–206 (1996)

  6. 6.

    & in Studies on Early Vertebrates (eds Arsenault, M., Lelièvre, H. & Janvier, P.) 373–388 (Bulletin du Muséum national d'histoire naturelle, Paris, 1995)

  7. 7.

    & Polydactyly in the earliest known tetrapod limbs. Nature 347, 66–69 (1990)

  8. 8.

    , & New insights into the postcranial skeleton of Ichthyostega. J. Vert. Paleontol. Abstr. 23, 41A (2003)

  9. 9.

    , & Localities, distribution and stratigraphical context of the Late Devonian tetrapods of East Greenland. Meddelelser øm Grønland Geosci. 43, 4–50 (2005)

  10. 10.

    et al. A uniquely specialised ear in a very early tetrapod. Nature 425, 65–69 (2003)

  11. 11.

    An early tetrapod from Romer's Gap. Nature 418, 72–76 (2002)

  12. 12.

    & A new primitive tetrapod, Whatcheeria deltae, from the Lower Carboniferous of Iowa. Palaeontology 38, 471–494 (1995)

  13. 13.

    & Pederpes finneyae, an articulated tetrapod from the Tournaisian of western Scotland. J. Syst. Palaeontol. 2, 311–346 (2005)

  14. 14.

    , & Early tetrapod relationships revisited. Biol. Rev. 78, 251–345 (2003)

  15. 15.

    The Carboniferous amphibian Proterogyrinus scheeli Romer, and the early evolution of tetrapods. Phil. Trans. R. Soc. Lond. B 306, 431–524 (1984)

  16. 16.

    The dermal skull roof of Acanthostega, an early tetrapod from the Late Devonian. Trans. R. Soc. Edinb. 93, 17–33 (2002)

Download references

Acknowledgements

We thank the Geological Museum and University of Copenhagen for access to their Ichthyostega material, and G. Cuny and D. Harper for their help and support during our visits. We would also like to acknowledge the late E. Jarvik and S. Bendix-Almgreen, both of whom gave us access to specimens then in their care. Preparation of MGUH f.n. 300 was carried out by S. Finney. M. Coates kindly permitted us to use one of his unpublished Acanthostega reconstructions for part of Fig. 1c. Most of our project was supported by an NERC grant with additional funding for H.B. provided by the Isaac Newton Trust Fund and by a project grant and salary from Vetenskapsrådet (the Swedish Research Council) for P.E.A.

Author information

Affiliations

  1. Subdepartment of Evolutionary Organismal Biology, Department of Physiology and Developmental Biology, Uppsala University, Norbyvägen 18A, 752 36 Uppsala, Sweden

    • Per Erik Ahlberg
    •  & Henning Blom
  2. Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK

    • Jennifer A. Clack
    •  & Henning Blom

Authors

  1. Search for Per Erik Ahlberg in:

  2. Search for Jennifer A. Clack in:

  3. Search for Henning Blom in:

Competing interests

Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

Corresponding author

Correspondence to Per Erik Ahlberg.

Supplementary information

Word documents

  1. 1.

    Supplementary Notes

    Discussion on preservation and taphonomy of the Ichthyostega material.

  2. 2.

    Supplementary Figure Legend

    Text to accompany Supplementary Figure S1.

Image files

  1. 1.

    Supplementary Figure S1

    This illustrates three thoracic and three lumbar neural arches from different Ichthyostega specimens.

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nature03893

Comments

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.