Structure and histogenesis of tooth plates in Sagenodus inaequalis Owen considered in relation to the phylogeny of post-Devonian dipnoans

Proceedings of the Royal Society of London. Series B, Containing Papers of a Biological Character
M M Smith


The histology of tooth plates of Sagenodus inaequalis has been investigated to obtain information on the histogenesis of the tissue. The histological mechanisms of growth and replacement of the tooth plate are described in terms of an increase in area of the tooth plate by addition of denticles to the lateral margins of the ridges, replacement of worn dentine at the tritoral surface by basal growth of dentine and invasive growth of dentine into the surrounding bone at the anterior and medial margins. The histogenesis of a specialized character for dipnoans is described, namely hypermineralized dentine, or petrodentine, within the tooth plates. This has placed an advanced character further back in the phylogenetic organization of dipnoans than was previously recognized. The implications of these observations are discussed in relation to proposed phylogenies and previous observations on tooth plates of other dipnoans. It is concluded that Sagenodus inaequalis shared a common ancestor with both the ceratondontids and the lepidosirenids. A sequence is proposed for the phyletic relationship of tooth plate-bearing dipnoans. From a consideration of the features of histogenesis of this specialized dentine, the alternative terminologies...Continue Reading


Oct 14, 1987·Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences·M M SmithK S Campbell
Oct 14, 1987·Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences·M M Smith, K S Campbell


Jan 1, 1978·Archives of Oral Biology·R P Shellis, D F Poole
Jul 1, 1976·Pharmacology, Biochemistry, and Behavior·W T Schmeling, M J Hosko
Jan 1, 1974·Cold Spring Harbor Symposia on Quantitative Biology·D D Brown, K Sugimoto
Feb 1, 1969·Biological Reviews of the Cambridge Philosophical Society·K S Thomson
Jul 1, 1961·Journal of Morphology·L RADINSKY

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