Abstract
Pycnogonids (sea spiders) are marine arthropods numbering some 1,160 extant species. They are globally distributed in depths of up to 6,000 metres, and locally abundant1,2; however, their typically delicate form and non-biomineralized cuticle has resulted in an extremely sparse fossil record that is not accepted universally3. There are two opposing views of their phylogenetic position: either within Chelicerata as sister group to the euchelicerates4,5,6,7, or as a sister taxon to all other euarthropods8. The Silurian Herefordshire Konservat-Lagerstätte9 in England (∼ 425 million years (Myr) bp) yields exceptionally preserved three-dimensional fossils that provide unrivalled insights into the palaeobiology of a variety of invertebrates10,11,12,13,14. The fossils are preserved as calcitic void in-fills in carbonate concretions within a volcaniclastic horizon15, and are reconstructed digitally12. Here we describe a new pycnogonid from this deposit, which is the oldest adult sea spider by ∼35 Myr and the most completely known fossil species. The large chelate first appendage is consistent with a chelicerate affinity for the pycnogonids. Cladistic analyses place the new species near the base of the pycnogonid crown group, implying that the latter had arisen by the Silurian period.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Rent or buy this article
Prices vary by article type
from$1.95
to$39.95
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
King, P. E. Pycnogonids (Hutchinson, London, 1973)
Arnaud, F. & Bamber, R. N. The biology of Pycnogonida. Adv. Mar. Biol. 24, 1–96 (1987)
Child, C. A. The marine fauna of New Zealand: Pycnogonida (sea spiders). Natl Inst. Water Atmos. Res. Biodiv. Memoir 109, 1–71 (1998)
Waloszek, D. & Dunlop, J. A. A larval sea spider (Arthropoda: Pycnogonida) from the Upper Cambrian ‘Orsten’ of Sweden, and the phylogenetic position of pycnogonids. Palaeontology 45, 421–446 (2002)
Vilpoux, K. & Waloszek, D. Larval development and morphogenesis of the sea spider Pycnogonum litorale (Ström, 1762) and the tagmosis of the body of Pantopoda. Arthrop. Struct. Dev. 32, 349–383 (2003)
Boxshall, G. A. The evolution of arthropod limbs. Biol. Rev. 79, 253–300 (2004)
Dunlop, J. A. & Arango, C. P. Pycnogonid affinities: a review. J. Zool. Syst. Evol. Res. (in the press)
Giribet, G., Edgecombe, G. D. & Wheeler, W. C. Arthropod phylogeny based on eight molecular loci and morphology. Nature 413, 157–161 (2001)
Briggs, D. E. G., Siveter, David J. & Siveter, Derek J. Soft-bodied fossils from a Silurian volcaniclastic deposit. Nature 382, 248–250 (1996)
Sutton, M. D., Briggs, D. E. G., Siveter, David J. & Siveter, Derek J. An exceptionally preserved vermiform mollusc from the Silurian of England. Nature 410, 461–463 (2001)
Sutton, M. D., Briggs, D. E. G., Siveter, David J. & Siveter, Derek J. A three-dimensionally preserved fossil polychaete worm from the Silurian of Herefordshire, England. Proc. R. Soc. Lond. B 268, 2355–2363 (2001)
Sutton, M. D., Briggs, D. E. G., Siveter, David J., Siveter, Derek J. & Orr, P. J. The arthropod Offacolus kingi (Chelicerata) from the Silurian of Herefordshire, England: computer based morphological reconstructions and phylogenetic affinities. Proc. R. Soc. Lond. B 269, 1195–1203 (2002)
Siveter, David J., Sutton, M. D., Briggs, D. E. G. & Siveter, Derek J. An ostracode crustacean with soft parts from the Lower Silurian. Science 302, 1749–1751 (2003)
Briggs, D. E. G., Sutton, M. D., Siveter, David J. & Siveter, Derek J. A new phyllocarid (Crustacea: Malacostraca) from the Silurian Fossil-Lagerstätte of Herefordshire, UK. Proc. R. Soc. Lond. B 271, 131–138 (2004)
Orr, P. J., Briggs, D. E. G., Siveter, David J. & Siveter, Derek J. Three-dimensional preservation of a non-biomineralized arthropod in concretions in Silurian volcaniclastic rocks from Herefordshire, England. J. Geol. Soc. Lond. 157, 173–186 (2000)
Miyazaki, K. J. On the shape of the foregut lumen in sea spiders (Arthropoda: Pycnogonida). Mar. Biol. Ass. UK 82, 1037–1038 (2002)
Bergström, J., Stürmer, W. & Winter, G. Palaeoisopus, Palaeopantopus and Palaeothea, pycnogonid arthropods from the Lower Devonian Hunsrück Slate, West Germany. Paläont. Zeit. 54, 7–54 (1980)
Bartels, C., Briggs, D. E. G. & Brassel, G. The Fossils of the Hunsrück Slate (Cambridge Univ. Press, 1998)
Wilby, P. R., Briggs, D. E. G. & Riou, B. Mineralization of soft-bodied invertebrates in a Jurassic metalliferous deposit. Geology 24, 847–850 (1996)
Arango, C. P. Morphological phylogenetics of the sea spiders (Arthropoda: Pycnogonida). Org. Divers. Evol. 2, 107–125 (2002)
Arango, C. P. Molecular approach to the phylogenetics of sea spiders (Arthropoda: Pycnogonida) using partial sequences of nuclear ribosomal DNA. Mol. Phylogenet. Evol. 28, 588–600 (2003)
Acknowledgements
This work was supported by the Leverhulme Trust, NERC and English Nature. K. Saunders is thanked for technical assistance; C. Arango, R. Bamber and D. Waloszek for discussion; G. Boxshall, J. Dunlop and D. Waloszek for pre-prints of their papers; S. de Grave for providing Recent material; and R. Fenn, T. Hall and J. Sinclair for general assistance.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Competing interests
The authors declare that they have no competing financial interests.
Supplementary information
Supplementary Figure 1
Expansion of Figure 2; cladogram of pycnogonids including fossil taxa (see Figure 2 for legend). (JPG 117 kb)
Supplementary Methods
Details of methodology for cladistic analyses. (DOC 20 kb)
Supplementary Note 1
Details of functional argument for interpretation of walking-leg segmentation. (DOC 21 kb)
Supplementary Note 2
Details of general functional morphology and mode of life. (DOC 29 kb)
Supplementary Table 1
Data matrix and character definitions for cladistic analyses. (XLS 49 kb)
Supplementary Video 1
Movie comprising serial grinding images from OUM C.29571. Slice interval is 20 µm, field of view horizontally is 5.15 mm. (MP4 912 kb)
Rights and permissions
About this article
Cite this article
Siveter, D., Sutton, M., Briggs, D. et al. A Silurian sea spider. Nature 431, 978–980 (2004). https://doi.org/10.1038/nature02928
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/nature02928
This article is cited by
-
Variations in preservation of exceptional fossils within concretions
Swiss Journal of Palaeontology (2023)
-
The visual pathway in sea spiders (Pycnogonida) displays a simple serial layout with similarities to the median eye pathway in horseshoe crabs
BMC Biology (2022)
-
First description of epimorphic development in Antarctic Pallenopsidae (Arthropoda, Pycnogonida) with insights into the evolution of the four-articled sea spider cheliphore
Zoological Letters (2019)
-
From egg to “no-body”: an overview and revision of developmental pathways in the ancient arthropod lineage Pycnogonida
Frontiers in Zoology (2017)
-
Dissecting a neuron network: FIB-SEM-based 3D-reconstruction of the visual neuropils in the sea spider Achelia langi (Dohrn, 1881) (Pycnogonida)
BMC Biology (2014)
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.