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    Pattern formation in development of chondrichthyan dentitions: a review of an evolutionary model

    Smith, M.M. and Johanson, Z. and Underwood, Charlie J. and Diekwisch, T.G.H. (2013) Pattern formation in development of chondrichthyan dentitions: a review of an evolutionary model. Historical Biology: An International Journal of Paleobiology 25 (2), pp. 127-142. ISSN 0891-2963.

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    The mode of tooth development displayed in Chondrichthyans (sharks, rays and holocephalans), one of frequent tooth replacement, was possible once a dental lamina had evolved, and since 1982 this has been known as the odontode regulation theory after Reif. Today, Reif's concepts need to be transformed into those of modern biology, the crosstalk between epithelium and mesenchyme, for the regulation of timing, spacing and shape of vertebrate teeth. Although Reif's proposed ‘primordial tissue’ may be the only site of progenitor cells, to restrict odontogenic potential to time-specific sites (protogerms), as has been suggested in the sequential addition tooth (SAT) model, very little data are available. Here, his model of alternate tooth replacement files has been interpreted as an integrated tooth addition unit of two adjacent files (SAT) unit for alternate replacement of teeth, regulated by putative, precisely timed gene expression for activation and inhibition. We have provided new data on patterns of tooth succession in dentitions of extant sharks and rays to compare with those of Reif. Using a phylogeny combined from molecular and morphological data, it is suggested that the alternate tooth addition and replacement model is derived within Chondrichthyes, and diversified from single file tooth addition of the stem chondrichthyans.


    Item Type: Article
    Keyword(s) / Subject(s): evolution and development, vertebrate dentition, chondrichthyan teeth, tooth replacement, sharks and rays, pattern regulation
    School: Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences
    Depositing User: Sarah Hall
    Date Deposited: 02 Jun 2016 12:45
    Last Modified: 02 Aug 2023 17:24


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