Phylogeny, classification and character polarity of the Osteostraci (Vertebrata)

  title={Phylogeny, classification and character polarity of the Osteostraci (Vertebrata)},
  author={Robert S. Sansom},
  journal={Journal of Systematic Palaeontology},
  pages={115 - 95}
  • Robert S. Sansom
  • Published 1 March 2009
  • Biology, Environmental Science
  • Journal of Systematic Palaeontology
Synopsis The jawless Osteostraci are the sister taxon to jawed vertebrates and, thus, are integral to understanding the evolution of gnathostomes from a jawless ancestor. Our understanding of this episode is currently hampered by incomplete knowledge of osteostracan phylogenetics and character polarity. Previous hypotheses of osteostracan intrarelations are reviewed and synthesised into two conflicting hypotheses ‐ ’Tremataspis‐basal’ versus ’Ateleaspis‐basal’ models, both related to the… 

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Conodont affinity and chordate phylogeny

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The phylogeny of the Craniata, with particular reference to the significance of fossil “agnathans”

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The anatomy of Turinia pagei (Powrie), and the phylogenetic status of the Thelodonti

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On Cephalaspis magnifica Traquair, 1893, from the Middle Devonian of Scotland, and the relationships of the last osteostracans

  • P. JanvierM. Newman
  • Environmental Science
    Earth and Environmental Science Transactions of the Royal Society of Edinburgh
  • 2004
The large Middle Devonian osteostracan Cephalaspis magnifica Traquair, 1893a, from the Late Eifelian Upper Caithness Flagstone Group of Caithness, Scotland, is redescribed on the basis of the

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The composition of the arandaspid dermoskeleton is common to heterostracans and astraspids, supporting existing hypotheses of early vertebrate phylogeny and emphasizing the peculiarity of existing interpretations of aranadaspid anatomy.

Environmental framework of the diversification of the Osteostraci during the Silurian and Devonian

The case of the Osteostraci, a group of fossil jawless vertebrates, is examined in detail to show whether or not its phylogenetic pattern displays a radiation that coincides with the extension of the Old Red Sandstone facies over the North Atlantic continent.