Presence of plicidentine in the oral teeth of the coelacanth Latimeria chalumnae Smith 1939 (Sarcopterygii; Actinistia).
The extant coelacanth Latimeria is a sarcopterygian predatory fish with caniniform teeth on its upper and lower jaws. The teeth are constituted of a cone of dentine with an apical cap of enamel, and they are fixed to the osseous component of the jaws by an attachment bone. Internal walls of the tooth base show folds that have been firstly interpreted in the past as radial vascular canals. Three-dimensional visualisation of these foldings using X-ray tomographic techniques and new histological interpretation lead to reconsider these structures as true plicidentine. The folds of the dentine do not invade the whole pulp cavity of the tooth contrary to the plicated condition of most fossil sarcopterygian fishes (e.g., Eusthenopteron, Porolepis, Megalichthys) certain fossil marine reptiles (ichthyosaurs) and extant varanids; in Latimeria they are limited to the lower third to the half of the pulp cavity. The presence of plicidentine in Latimeria's teeth is proposed to be a plesiomorphic character for sarcopterygians.
UMR 7208 (CNRS-IRD-MNHN-UPMC), BOREA, Département des Milieux et Peuplements Aquatiques, Muséum national d'Histoire naturelle, C.P. 026, 43 rue Cuvier, 75231 Paris cedex 05, France. Electronic address: meunier@mnhn.fr.
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Meunier
UMR Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (UMR CR2P), Sorbonne Universités, Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Université Pierre et Marie Curie Paris6, C.P. 38, 57 rue Cuvier, 75231 Paris cedex 05, France. Electronic address: mondejar@mnhn.fr.
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Mondéjar-Fernández
UMR Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (UMR CR2P), Sorbonne Universités, Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Université Pierre et Marie Curie Paris6, C.P. 38, 57 rue Cuvier, 75231 Paris cedex 05, France. Electronic address: goussard@mnhn.fr.
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Goussard
UMR Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (UMR CR2P), Sorbonne Universités, Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Université Pierre et Marie Curie Paris6, C.P. 38, 57 rue Cuvier, 75231 Paris cedex 05, France. Electronic address: gclement@mnhn.fr.
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Clément
UMR 7179 - (CNRS-MNHN), Mécanismes adaptatifs des organismes aux communautés, Département Écologie et Gestion de la Biodiversité, Muséum national d'Histoire naturelle, C.P. 055, 57 rue Cuvier, 75231 Paris cedex 05, France. Electronic address: herbin@mnhn.fr.
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Herbin
D000818:Animals; D003804:Dentin / Q000648:ultrastructure*; D005260:Female; D005399:Fishes / Q000033:anatomy & histology*; D021621:Imaging, Three-Dimensional; D014070:Tooth / Q000648:ultrastructure*
Evolution; Histology; Latimeria; Plicidentine; Tooth