Paired gill slits in a fossil with a calcite skeleton

@article{Dominguez2002PairedGS,
  title={Paired gill slits in a fossil with a calcite skeleton},
  author={Patr{\'i}cio Dominguez and Antone G. Jacobson and Richard P.S. Jefferies},
  journal={Nature},
  year={2002},
  volume={417},
  pages={841-844}
}
The chordates, hemichordates (such as acorn worms) and echinoderms (such as starfish) comprise the group Deuterostomia, well established as monophyletic. Among extant deuterostomes, a skeleton in which each plate has the crystallographic structure of a single crystal of calcite is characteristic of echinoderms and is always associated with radial symmetry and never with gill slits. Among fossils, however, such a skeleton sometimes occurs without radial symmetry. This is true of Jaekelocarpus… 

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References

SHOWING 1-10 OF 45 REFERENCES

The youngest carpoid: occurrence, affinities, and life mode of a Pennsylvanian (Morrowan) mitrate from Oklahoma

Abundant, well-preserved specimens of a new peltocystidan mitrate carpoid, Jaekelocarpus oklahomensis n. gen. and sp., have been discovered in the Pennsylvanian (Morrowan Series) Gene Autry Shale

CARPOIDS—ECHINODERMS OR CHORDATES?

For the purposes of this review the term ‘carpoid’ is used to include such animals, known generally as the cornute and mitrate carpoids, but now either referred to the echinoderm class Stylophora or the chordate subphylum Calcichordata.

Evolution of the chordate body plan: new insights from phylogenetic analyses of deuterostome phyla.

The nesting of the pterobranchs within the enteropneusts dramatically alters the view of the evolution of the chordate body plan and suggests that the ancestral deuterostome more closely resembled a mobile worm-like enteropNEust than a sessile colonial pterOBranch.

An episode in the ancestry of vertebrates: From mitrate to crown‐group craniate

This paper describes a stem-craniate mitrate, and reconstructs, from the shared characteristics of the extant craniates supplemented by evidence from fossils, the latest common ancestor of extant crANIates which it is called “animal x”.

A new stem-group chordate (Cornuta) from the Llandeilo of Czechoslovakia and the cornute-mitrate transition

It is concluded that P. mergli reinforces the view that the convex surface of the mitrates was ventral in life, and a new homology proposed between the anterior ventral fore-tail plates of cornutes and what were formerly called plates g and j of mitrates.

Brief review of the stylophoran debate

  • M. Ruta
  • Biology
    Evolution & development
  • 1999
Stylophorans may lie at the base of the echinoderm clade and primitively lack pentameral symmetry, therefore casting light on the near‐ancestral body organization of the phylum.

Echinoderm phylogeny and evolutionary biology

This book discusses the phylogeny of the cystoids, the evolutionary palaeoecology of the Blaistoidea, and the early evolution of the Crinoidea ontogeny and phylogenY of disparid crinoids, as well as the origins of the deep-sea hoasteroid fauna feeding and respiratory strategies in stylophora.

Animal phylogeny and the ancestry of bilaterians: inferences from morphology and 18S rDNA gene sequences

Because chaetognaths and lophophorates, taxa traditionally allied with deuterostomes, occupy basal positions within their respective protostomian clades, deuterstomy most likely represents a suite of characters plesiomorphic for bilaterians.

In defence of the calcichordates

The present paper answers Philip's criticisms of the calcichordate interpretation and discusses his own proposals and his comments on Ubaghs' views.