Advanced search
1 file | 7.86 MB

Anomalocaridid trunk limb homology revealed by a giant filter-feeder with paired flaps

(2015) NATURE. 522(7554). p.77-U178
Author
Organization
Abstract
Exceptionally preserved fossils from the Palaeozoic era provide crucial insights into arthropod evolution, with recent discoveries bringing phylogeny and character homology into sharp focus(1-4). Integral to such studies are anomalocaridids, a clade of stem arthropods whose remarkable morphology illuminates early arthropod relationships(5,6) and Cambrian ecology(7-9). Although recent work has focused on the anomalocaridid head(6-10), the nature of their trunk has been debated widely(5,11-18). Here we describe new anomalocaridid(17) specimens from the Early Ordovician Fezouata Biota of Morocco(19), which not only show well-preserved head appendages providing key ecological data, but also elucidate the nature of anomalocaridid trunk flaps, resolving their homology with arthropod trunk limbs. The new material shows that each trunk segment bears a separate dorsal and ventral pair of flaps, with a series of setal blades attached at the base of the dorsal flaps. Comparisons with other stem lineage arthropods(16,20-22) indicate that anomalocaridid ventral flaps are homologous with lobopodous walking limbs and the endopod of the euarthropod biramous limb, whereas the dorsal flaps and associated setal blades are homologous with the flaps of gilled lobopodians (for example, Kerygmachela kierkegaardi, Pambdelurion whittingtoni) and exites of the 'Cambrian biramous limb'(23). This evidence shows that anomalocaridids represent a stage before the fusion of exite and endopod into the 'Cambrian biramous limb'(5,16,23), confirming their basal placement in the euarthropod stem(4-6), rather than in the arthropod crown(24) or with cycloneuralian worms(14). Unlike other anomalocaridids, the Fezouata taxon combines head appendages convergently(9) adapted for filter-feeding with an unprecedented body length exceeding 2 m, indicating a new direction in the feeding ecology of the clade. The evolution of giant filter-feeding anomalocaridids may reflect the establishment of highly developed planktic ecosystems during the Great Ordovician Biodiversification Event(25).
Keywords
ARTHROPOD, BURGESS SHALE, APPENDAGES, EVOLUTION, MORPHOLOGY, OPABINIA, PREDATORS, GREENLAND, AFFINITY, BRAIN

Downloads

  • (...).pdf
    • full text
    • |
    • UGent only
    • |
    • PDF
    • |
    • 7.86 MB

Citation

Please use this url to cite or link to this publication:

Chicago
Van Roy, Peter, Allison C Daley, and Derek EG Briggs. 2015. “Anomalocaridid Trunk Limb Homology Revealed by a Giant Filter-feeder with Paired Flaps.” Nature 522 (7554): 77–U178.
APA
Van Roy, P., Daley, A. C., & Briggs, D. E. (2015). Anomalocaridid trunk limb homology revealed by a giant filter-feeder with paired flaps. NATURE, 522(7554), 77–U178.
Vancouver
1.
Van Roy P, Daley AC, Briggs DE. Anomalocaridid trunk limb homology revealed by a giant filter-feeder with paired flaps. NATURE. 2015;522(7554):77–U178.
MLA
Van Roy, Peter, Allison C Daley, and Derek EG Briggs. “Anomalocaridid Trunk Limb Homology Revealed by a Giant Filter-feeder with Paired Flaps.” NATURE 522.7554 (2015): 77–U178. Print.
@article{6852277,
  abstract     = {Exceptionally preserved fossils from the Palaeozoic era provide crucial insights into arthropod evolution, with recent discoveries bringing phylogeny and character homology into sharp focus(1-4). Integral to such studies are anomalocaridids, a clade of stem arthropods whose remarkable morphology illuminates early arthropod relationships(5,6) and Cambrian ecology(7-9). Although recent work has focused on the anomalocaridid head(6-10), the nature of their trunk has been debated widely(5,11-18). Here we describe new anomalocaridid(17) specimens from the Early Ordovician Fezouata Biota of Morocco(19), which not only show well-preserved head appendages providing key ecological data, but also elucidate the nature of anomalocaridid trunk flaps, resolving their homology with arthropod trunk limbs. The new material shows that each trunk segment bears a separate dorsal and ventral pair of flaps, with a series of setal blades attached at the base of the dorsal flaps. Comparisons with other stem lineage arthropods(16,20-22) indicate that anomalocaridid ventral flaps are homologous with lobopodous walking limbs and the endopod of the euarthropod biramous limb, whereas the dorsal flaps and associated setal blades are homologous with the flaps of gilled lobopodians (for example, Kerygmachela kierkegaardi, Pambdelurion whittingtoni) and exites of the 'Cambrian biramous limb'(23). This evidence shows that anomalocaridids represent a stage before the fusion of exite and endopod into the 'Cambrian biramous limb'(5,16,23), confirming their basal placement in the euarthropod stem(4-6), rather than in the arthropod crown(24) or with cycloneuralian worms(14). Unlike other anomalocaridids, the Fezouata taxon combines head appendages convergently(9) adapted for filter-feeding with an unprecedented body length exceeding 2 m, indicating a new direction in the feeding ecology of the clade. The evolution of giant filter-feeding anomalocaridids may reflect the establishment of highly developed planktic ecosystems during the Great Ordovician Biodiversification Event(25).},
  author       = {Van Roy, Peter and Daley, Allison C and Briggs, Derek EG},
  issn         = {0028-0836},
  journal      = {NATURE},
  keyword      = {ARTHROPOD,BURGESS SHALE,APPENDAGES,EVOLUTION,MORPHOLOGY,OPABINIA,PREDATORS,GREENLAND,AFFINITY,BRAIN},
  language     = {eng},
  number       = {7554},
  pages        = {77--U178},
  title        = {Anomalocaridid trunk limb homology revealed by a giant filter-feeder with paired flaps},
  url          = {http://dx.doi.org/10.1038/nature14256},
  volume       = {522},
  year         = {2015},
}

Altmetric
View in Altmetric
Web of Science
Times cited: