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Exceptionally prolonged tooth formation in elasmosaurid plesiosaurians

Elasmosaurid plesiosaurians were globally prolific marine reptiles that dominated the Mesozoic seas for over 70 million years. Their iconic body-plan incorporated an exceedingly long neck and small skull equipped with prominent intermeshing ‘fangs’. How this bizarre dental apparatus was employed in...

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Autores principales: Kear, Benjamin P., Larsson, Dennis, Lindgren, Johan, Kundrát, Martin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5328283/
https://www.ncbi.nlm.nih.gov/pubmed/28241059
http://dx.doi.org/10.1371/journal.pone.0172759
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author Kear, Benjamin P.
Larsson, Dennis
Lindgren, Johan
Kundrát, Martin
author_facet Kear, Benjamin P.
Larsson, Dennis
Lindgren, Johan
Kundrát, Martin
author_sort Kear, Benjamin P.
collection PubMed
description Elasmosaurid plesiosaurians were globally prolific marine reptiles that dominated the Mesozoic seas for over 70 million years. Their iconic body-plan incorporated an exceedingly long neck and small skull equipped with prominent intermeshing ‘fangs’. How this bizarre dental apparatus was employed in feeding is uncertain, but fossilized gut contents indicate a diverse diet of small pelagic vertebrates, cephalopods and epifaunal benthos. Here we report the first plesiosaurian tooth formation rates as a mechanism for servicing the functional dentition. Multiple dentine thin sections were taken through isolated elasmosaurid teeth from the Upper Cretaceous of Sweden. These specimens revealed an average of 950 daily incremental lines of von Ebner, and infer a remarkably protracted tooth formation cycle of about 2–3 years–other polyphyodont amniotes normally take ~1–2 years to form their teeth. Such delayed odontogenesis might reflect differences in crown length and function within an originally uneven tooth array. Indeed, slower replacement periodicity has been found to distinguish larger caniniform teeth in macrophagous pliosaurid plesiosaurians. However, the archetypal sauropterygian dental replacement system likely also imposed constraints via segregation of the developing tooth germs within discrete bony crypts; these partly resorbed to allow maturation of the replacement teeth within the primary alveoli after displacement of the functional crowns. Prolonged dental formation has otherwise been linked to tooth robustness and adaption for vigorous food processing. Conversely, elasmosaurids possessed narrow crowns with an elongate profile that denotes structural fragility. Their apparent predilection for easily subdued prey could thus have minimized this potential for damage, and was perhaps coupled with selective feeding strategies that ecologically optimized elasmosaurids towards more delicate middle trophic level aquatic predation.
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spelling pubmed-53282832017-03-09 Exceptionally prolonged tooth formation in elasmosaurid plesiosaurians Kear, Benjamin P. Larsson, Dennis Lindgren, Johan Kundrát, Martin PLoS One Research Article Elasmosaurid plesiosaurians were globally prolific marine reptiles that dominated the Mesozoic seas for over 70 million years. Their iconic body-plan incorporated an exceedingly long neck and small skull equipped with prominent intermeshing ‘fangs’. How this bizarre dental apparatus was employed in feeding is uncertain, but fossilized gut contents indicate a diverse diet of small pelagic vertebrates, cephalopods and epifaunal benthos. Here we report the first plesiosaurian tooth formation rates as a mechanism for servicing the functional dentition. Multiple dentine thin sections were taken through isolated elasmosaurid teeth from the Upper Cretaceous of Sweden. These specimens revealed an average of 950 daily incremental lines of von Ebner, and infer a remarkably protracted tooth formation cycle of about 2–3 years–other polyphyodont amniotes normally take ~1–2 years to form their teeth. Such delayed odontogenesis might reflect differences in crown length and function within an originally uneven tooth array. Indeed, slower replacement periodicity has been found to distinguish larger caniniform teeth in macrophagous pliosaurid plesiosaurians. However, the archetypal sauropterygian dental replacement system likely also imposed constraints via segregation of the developing tooth germs within discrete bony crypts; these partly resorbed to allow maturation of the replacement teeth within the primary alveoli after displacement of the functional crowns. Prolonged dental formation has otherwise been linked to tooth robustness and adaption for vigorous food processing. Conversely, elasmosaurids possessed narrow crowns with an elongate profile that denotes structural fragility. Their apparent predilection for easily subdued prey could thus have minimized this potential for damage, and was perhaps coupled with selective feeding strategies that ecologically optimized elasmosaurids towards more delicate middle trophic level aquatic predation. Public Library of Science 2017-02-27 /pmc/articles/PMC5328283/ /pubmed/28241059 http://dx.doi.org/10.1371/journal.pone.0172759 Text en © 2017 Kear et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Kear, Benjamin P.
Larsson, Dennis
Lindgren, Johan
Kundrát, Martin
Exceptionally prolonged tooth formation in elasmosaurid plesiosaurians
title Exceptionally prolonged tooth formation in elasmosaurid plesiosaurians
title_full Exceptionally prolonged tooth formation in elasmosaurid plesiosaurians
title_fullStr Exceptionally prolonged tooth formation in elasmosaurid plesiosaurians
title_full_unstemmed Exceptionally prolonged tooth formation in elasmosaurid plesiosaurians
title_short Exceptionally prolonged tooth formation in elasmosaurid plesiosaurians
title_sort exceptionally prolonged tooth formation in elasmosaurid plesiosaurians
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5328283/
https://www.ncbi.nlm.nih.gov/pubmed/28241059
http://dx.doi.org/10.1371/journal.pone.0172759
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