Growth patterns in euconodont crown enamel: implications for life history and mode-of-life reconstruction in the earliest vertebrates

Proceedings. Biological Sciences
H A Armstrong, C J Smith

Abstract

Euconodonts were the first vertebrates to produce a mineralized skeleton. It is concluded that the minor increments in the crown enamels of Protopanderodus varicostatus and Drepanodus robustus are probable homologues of the cross striations in hominoid enamel, although they are much more variable in thickness and represent daily to weekly growth. Major increments are superficially similar to lines of Retzuis, but represent a check in growth that is likely to have occurred at monthly intervals. Periods of above- and below-average growth are likely to have been seasonally moderated. The growth of P. varicostatus' elements are characterized by two distinct phases: the production of a triangular, asymmetrical juvenile 'proto-element' followed, in a second phase, by the development of the curved and twisted geometry of the adult element. These fundamentally different morphologies imply that juvenile and adult animals had different modes of life and/or feeding strategies. In these animals the growth of the elements was indeterminate. The growth model for euconodonts is clearly different from that of hominoid teeth as the enamel organ must have reformed repeatedly throughout life.

References

May 29, 1992·Science·I J SansomM M Smith
Jul 6, 2000·Biological Reviews of the Cambridge Philosophical Society·P C DonoghueR J Aldridge

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Citations

Aug 24, 2010·BioEssays : News and Reviews in Molecular, Cellular and Developmental Biology·Gareth J FraserJ Todd Streelman
Dec 6, 2008·Evolution; International Journal of Organic Evolution·Daniel S Moen, John J Wiens
Aug 12, 2009·Evolution; International Journal of Organic Evolution·Daniel S MoenJohn J Wiens
Nov 13, 2009·Molecular Microbiology·Arvind G KinhikarSuman Laal
Jul 14, 2010·Diabetologia·J H PinkneyE A M Gale
Jul 8, 2007·Cognitive Science·Ping LiBrian Mac Whinney
May 21, 2013·Annual Review of Phytopathology·Richard W MichelmoreKatherine S Caldwell
Jul 9, 2014·Annual Review of Phytopathology·Lynn Epstein
Sep 7, 2018·Proceedings. Biological Sciences·Bryan ShirleyEmilia Jarochowska

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