Letter | Published:

Paired gill slits in a fossil with a calcite skeleton

Nature volume 417, pages 841844 (20 June 2002) | Download Citation



The chordates, hemichordates (such as acorn worms) and echinoderms (such as starfish) comprise the group Deuterostomia, well established as monophyletic1,2. Among extant deuterostomes, a skeleton in which each plate has the crystallographic structure of a single crystal of calcite is characteristic of echinoderms and is always associated with radial symmetry and never with gill slits. Among fossils, however, such a skeleton sometimes occurs without radial symmetry. This is true of Jaekelocarpus oklahomensis, from the Upper Carboniferous of Oklahoma, USA, which, being externally almost bilaterally symmetrical, is traditionally placed in the group Mitrata (Ordovician to Carboniferous periods, 530–280 million years ago), by contrast with the bizarrely asymmetrical Cornuta (Cambrian to Ordovician periods, 540 to 440 million years ago). Using computer X-ray microtomography, we describe the anatomy of Jaekelocarpus in greater detail than formerly possible, reveal evidence of paired gill slits internally and interpret its functional anatomy. On this basis we suggest its phylogenetic position within the deuterostomes.

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We are grateful to E. Nesbitt and R. Eng for making the specimens of Jaekelocarpus available and to T. Rowe and his co-workers for their collaboration. P.D. was supported on a post-doctoral fellowship in London by the Spanish Government (Ministerio de Educación, Cultura y Deportes).

Author information


  1. *Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK

    • Patrício Dominguez
    •  & Richard P. S. Jefferies
  2. ‡Patterson Labs, MCDB, The University of Texas, Austin, Texas 78712, USA

    • Antone G. Jacobson
  3. †Departamento de Paleontologia, Universidad Complutense de Madrid, Ciudad Universitaría, 28040 Madrid, Spain

    • Patrício Dominguez


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Competing interests

The authors declare that they have no competing financial interests.

Corresponding author

Correspondence to Richard P. S. Jefferies.

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    Links, descriptions and screenshots to supplementary movies 1 - 9

    The original TIFF files showing the serial X-ray sections of Jackelocarpus are also stored in the Digital Morphology site of the University of Texas and can be accessed on http://www.digimorph.org

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