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Tooth histology in the cretaceous ichthyosaur Platypterygius australis , and its significance for the conservation and divergence of mineralized tooth tissues in amniotes
Author(s) -
Maxwell Erin E.,
Caldwell Michael W.,
Lamoureux Denis O.
Publication year - 2011
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.10898
Subject(s) - cementum , biology , anatomy , mineralized tissues , cretaceous , paleontology , dentistry , dentin , medicine
Ichthyosaurs are an extinct group of secondarily aquatic reptiles that show ligamentous tooth attachment to the jaw in some derived forms. Here, we provide a modern description of tooth histology in ichthyosaurs, using Platypterygius australis , a large ichthyosaur from the Cretaceous of Australia. Our study supports evolutionary conservation of the principal mineralized tooth tissue types in amniotes with ligamentous tooth attachment: enamel, dentine, cellular, and acellular cementum. This is the first time that the latter tissue has been located in ichthyosaurs. Vascularized cementum (osteocementum) is reduced or absent in amniotes in which the teeth are ankylosed to the jaw bone, such as basal ichthyosaurs, and raises questions regarding the function of this tissue and the potential developmental or selective conditions leading to its convergent evolution. J. Morphol., 2011. © 2010 Wiley‐Liss, Inc.