The morphology of Opabinia regalis and the reconstruction of the arthropod stem‐group

@article{Budd1996TheMO,
  title={The morphology of Opabinia regalis and the reconstruction of the arthropod stem‐group},
  author={Graham E. Budd},
  journal={Lethaia},
  year={1996},
  volume={29},
  pages={1-14}
}
  • G. Budd
  • Published 1 March 1996
  • Geography, Biology
  • Lethaia
Opabinia regalis Walcott is an enigmatic fossil from the Middle Cambrian Burgess Shale of uncertain affinities. Recent suggestions place it in a clade with Anomalocaris Whiteaves from the Burgess Shale and Kerygmachela Budd from the Greenlandic Sirius Passet Fauna; these taxa have been interpreted as ‘lobopods’. Consideration of available Opabinia specimens demonstrates that reflective extensions from the axial region, previously thought to be either gut diverticula or musculature, can be… 

The nature and significance of the appendages of Opabinia from the Middle Cambrian Burgess Shale

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A new hypothesis for the origin of the arthropod biramous limb from an exopod like that in Opabinia is presented, which involves an endite-bearing phyllopodous limb as an intermediate stage.

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  • G. Budd
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    Transactions of the Royal Society of Edinburgh: Earth Sciences
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Stem group arthropods from the Lower Cambrian Sirius Passet fauna of North Greenland

  • G. Budd
  • Geography, Environmental Science
  • 1998
Discussion of fossil evidence for the origin and early evolution of the arthropods has been dominated for many years by the evidence from the Middle Cambrian Burgess Shale from British Columbia

THE SYSTEMATICS AND PHYLOGENETIC RELATIONSHIPS OF VETULICOLIANS

TLDR
It is not possible on current evidence to reach an unequivocal conclusion regarding the phylogenetic position of the vetulicolians, but one possibility is that they are a sister group of arthropods that lost limbs but gained gill structures analogous to those of deuterostomes, but several features remain unexplained by this model.
...

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