The hexamer hypothesis explains apparent irregularities in the plating of early and extant crinoids
Department of Psychology and Sports Science, University of Münster, Münster, Germany
- Published
- Accepted
- Subject Areas
- Developmental Biology, Paleontology
- Keywords
- Early crinoids, fossil, embryology, Bauplan, Extraxial axial theory (EAT), evolution
- Copyright
- © 2015 de Lussanet
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
- Cite this article
- 2015. The hexamer hypothesis explains apparent irregularities in the plating of early and extant crinoids. PeerJ PrePrints 3:e857v1 https://doi.org/10.7287/peerj.preprints.857v1
Abstract
In 2011, I proposed a new hypothesis for the evolution and development of the five-rayed structure of echinoderms, the Hexamer Hypothesis (Lussanet, 2011). According to this hypothesis, the five-rayed structure develops by reduction from a six-rayed Bauplan. Crinoids (sea lilies) are unique as the only extant clade with stalked representatives, reaching back at least to the early Ordovician. Their extraordinary rich fossil record and the known embryology of recent forms make them ideal to test the Hexamer Hypothesis. It is concluded that the plating of the calyx and the stalk can be explained by the new hypothesis.
Author Comment
This is an accepted preprint for the Progress in Echinoderm Palaeobiology conference (Spain 2015).