A giant Ordovician anomalocaridid

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Anomalocaridids, giant lightly sclerotized invertebrate predators, occur in a number of exceptionally preserved early and middle Cambrian (542–501million years ago) biotas and have come to symbolize the unfamiliar morphologies displayed by stem organisms in faunas of the Burgess Shale type. They are characterized by a pair of anterior, segmented appendages, a circlet of plates around the mouth, and an elongate segmented trunk lacking true tergites with a pair of flexible lateral lobes per segment1, 2. Disarticulated body parts, such as the anterior appendages and oral circlet, had been assigned to a range of taxonomic groups—but the discovery of complete specimens from the middle Cambrian Burgess Shale showed that these disparate elements all belong to a single kind of animal3. Phylogenetic analyses support a position of anomalocaridids in the arthropod stem, as a sister group to the euarthropods4, 5, 6. The anomalocaridids were the largest animals in Cambrian communities. The youngest unequivocal examples occur in the middle Cambrian Marjum Formation of Utah7 but an arthropod retaining some anomalocaridid characteristics is present in the Devonian of Germany5. Here we report the post-Cambrian occurrence of anomalocaridids, from the Early Ordovician (488–472million years ago) Fezouata Biota8 in southeastern Morocco, including specimens larger than any in Cambrian biotas. These giant animals were an important element of some marine communities for about 30million years longer than previously realized. The Moroccan specimens confirm the presence of a dorsal array of flexible blades attached to a transverse rachis on the trunk segments; these blades probably functioned as gills.


  1. Chen, J. Y., Ramsköld, L. & Zhou, G. Q. Evidence for monophyly and arthropod affinity of Cambrian giant predators. Science 264, 13041308 (1994)
  2. Collins, D. The “evolution” of Anomalocaris and its classification in the arthropod Class Dinocarida (nov.) and Order Radiodonta (nov.). J. Paleontol. 70, 280293 (1996)
  3. Whittington, H. B. & Briggs, D. E. G. The largest Cambrian animal, Anomalocaris, Burgess Shale, British Columbia. Phil. Trans. R. Soc. Lond. B 309, 569609 (1985)
  4. Budd, G. E. A Cambrian gilled lobopod from Greenland. Nature 364, 709711 (1993)
  5. Kühl, G., Briggs, D. E. G. & Rust, J. A great appendage arthropod with a radial mouth from the Lower Devonian Hunsrück Slate, Germany. Science 323, 771773 (2009)
  6. Daley, A. C., Budd, G. E., Caron, J.-B., Edgecombe, G. D. & Collins, D. The Burgess Shale anomalocaridid Hurdia and its significance for early euarthropod evolution. Science 323, 15971600 (2009)
  7. Briggs, D. E. G. & Robison, R. A. Exceptionally preserved nontrilobite arthropods and Anomalocaris from the Middle Cambrian of Utah. Univ. Kansas Paleont. Contrib. 111, 123 (1984)
  8. Van Roy, P. et al. Ordovician faunas of Burgess Shale type. Nature 465, 215218 (2010)
  9. Whiteaves, J. F. Description of a new genus and species of phyllocarid crustacean from the Middle Cambrian of Mount Stephen, British Columbia. Can. Rec. Sci. 5, 205208 (1892)
  10. Walcott, C. D. Middle Cambrian Merostomata. Cambrian geology and paleontology II. Smithson. Misc. Coll. 57, 1740 (1911)
  11. Walcott, C. D. Middle Cambrian Holothurians and Medusae. Cambrian geology and paleontology II. Smithson. Misc. Coll. 57, 4168 (1911)
  12. Walcott, C. D. Middle Cambrian Branchiopoda, Malacostraca, Trilobita, and Merostomata. Cambrian geology and paleontology II. Smithson. Misc. Coll. 57, 145228 (1912)
  13. Rolfe, W. D. I. Two new arthropod carapaces from the Burgess Shale (Middle Cambrian) of Canada. Breviora 160, 19 (1962)
  14. Hou, X., Bergström, J. & Yang, J. Distinguishing anomalocaridids from arthropods and priapulids. Geol. J. 41, 259269 (2006)
  15. Chen, J., Waloszek, D. & Maas, A. A new 'great-appendage' arthropod from the Lower Cambrian of China and homology of chelicerate chelicerae and raptorial antero-ventral appendages. Lethaia 37, 320 (2004)
  16. Dzik, J. & Lendzion, K. The oldest arthropods of the East European platform. Lethaia 21, 2938 (1988)
  17. Daley, A. C. & Budd, G. E. New anomalocaridid appendages from the Burgess Shale, Canada. Palaeontology 53, 721738 (2010)
  18. Ponomarenko, A. G. First record of Dinocarida from Russia. Paleontol. J. 44, 503504 (2010)
  19. Hou, X., Bergström, J. & Ahlberg, P. Anomalocaris and other large animals in the Lower Cambrian Chengjiang fauna of southwest China. Geol. För. Förh. 117, 163183 (1995)
  20. Daley, A. C. & Peel, J. S. A possible anomalocaridid from the Cambrian Sirius Passet Lagerstätte, north Greenland. J. Paleontol. 84, 352355 (2010)
  21. Masiak, M. & Zylinska, A. Burgess Shale-type fossils in Cambrian sandstones of the Holy Cross Mountains. Acta Palaeontol. Pol. 39, 329340 (1994)
  22. Van Roy, P. & Tetlie, O. E. A spinose appendage fragment of a problematic arthropod from the Early Ordovician of Morocco. Acta Palaeontol. Pol. 51, 239246 (2006)
  23. Vinther, J., Van Roy, P. & Briggs, D. E. G. Machaeridians are Palaeozoic armoured annelids. Nature 451, 185188 (2008)
  24. Fortey, R. A. A new giant asaphid trilobite from the Lower Ordovician of Morocco. Mem. Assoc. Austral. Palaeontol. 37, 916 (2009)
  25. Bergström, J. Opabinia and Anomalocaris, unique Cambrian ‘arthropods’. Lethaia 19, 241246 (1986)
  26. Bergström, J. The Cambrian Opabinia and Anomalocaris. Lethaia 20, 187188 (1987)
  27. Budd, G. E. & Daley, A. C. The lobes and lobopods of Opabinia regalis of the middle Cambrian Burgess Shale. Lethaia (in the press)
  28. Braddy, S. J., Poschmann, M. & Tetlie, O. E. Giant claw reveals the largest ever arthropod. Biol. Lett. 4, 106109 (2008)
  29. Hahn, G., Hahn, R. A. & Brauckmann, C. Zur Kenntis von Arthropleura (Myriapoda; Ober Karbon). Geol. Paleontol. 20, 125137 (1986)
  30. Servais, T., Owen, A. W., Harper, D. A. T., Kröger, B. & Munnecke, A. The Great Ordovician Biodiversification Event (GOBE): the palaeoecological dimension. Palaeogeogr. Palaeoclimatol. Palaeoecol. 294, 99119 (2010)

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  1. Department of Geology and Geophysics, Yale University, PO Box 208109, New Haven, Connecticut 06520, USA

    • Peter Van Roy &
    • Derek E. G. Briggs
  2. Research Unit Palaeontology, Department of Geology and Soil Science, Ghent University, Krijgslaan 281/S8, B-9000 Ghent, Belgium

    • Peter Van Roy
  3. Yale Peabody Museum of Natural History, Yale University, New Haven, Connecticut 06520, USA

    • Derek E. G. Briggs


The authors contributed equally to interpreting the fossils and writing the paper. P.V.R. played the primary role in field work, and prepared, photographed and drew the specimens.

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The authors declare no competing financial interests.

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