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Thecodont tooth attachment and replacement in bolosaurid parareptiles

Permian bolosaurid parareptiles are well-known for having complex tooth crowns and complete tooth rows in the jaws, in contrast to the comparatively simple teeth and frequent replacement gaps in all other Paleozoic amniotes. Analysis of the specialized dentition of the bolosaurid parareptiles Bolosa...

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Autores principales: Snyder, Adam J., LeBlanc, Aaron R.H., Jun, Chen, Bevitt, Joseph J., Reisz, Robert R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PeerJ Inc. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7229766/
https://www.ncbi.nlm.nih.gov/pubmed/32440377
http://dx.doi.org/10.7717/peerj.9168
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author Snyder, Adam J.
LeBlanc, Aaron R.H.
Jun, Chen
Bevitt, Joseph J.
Reisz, Robert R.
author_facet Snyder, Adam J.
LeBlanc, Aaron R.H.
Jun, Chen
Bevitt, Joseph J.
Reisz, Robert R.
author_sort Snyder, Adam J.
collection PubMed
description Permian bolosaurid parareptiles are well-known for having complex tooth crowns and complete tooth rows in the jaws, in contrast to the comparatively simple teeth and frequent replacement gaps in all other Paleozoic amniotes. Analysis of the specialized dentition of the bolosaurid parareptiles Bolosaurus from North America and Belebey from Russia, utilizing a combination of histological and tomographic data, reveals unusual patterns of tooth development and replacement. The data confirm that bolosaurid teeth have thecodont implantation with deep roots, the oldest known such example among amniotes, and independently evolved among much younger archosauromorphs (including dinosaurs and crocodilians) and among synapsids (including mammals). High-resolution CT scans were able to detect the density boundary between the alveolar bone and the jawbone, as confirmed by histology, and revealed the location and size of developing replacement teeth in the pulp cavity of functional teeth. Evidence provided by the paratype dentary of Belebey chengi indicates that replacement teeth are present along the whole tooth row at slightly different stages of development, with the ontogenetically more developed teeth anteriorly, suggesting that tooth replacement was highly synchronized. CT data also show tooth replacement is directly related to the presence of lingual pits in the jaw, and that migration of tooth buds occurs initially close to these resorption pits to a position immediately below the functional tooth within its pulp cavity. The size and complex shape of the replacement teeth in the holotype of Bolosaurus grandis indicate that the replacement teeth can develop within the pulp cavity to an advanced stage while the previous generation remains functional for an extended time, reminiscent of the condition seen in other amniotes with occluding dentitions, including mammals.
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spelling pubmed-72297662020-05-21 Thecodont tooth attachment and replacement in bolosaurid parareptiles Snyder, Adam J. LeBlanc, Aaron R.H. Jun, Chen Bevitt, Joseph J. Reisz, Robert R. PeerJ Evolutionary Studies Permian bolosaurid parareptiles are well-known for having complex tooth crowns and complete tooth rows in the jaws, in contrast to the comparatively simple teeth and frequent replacement gaps in all other Paleozoic amniotes. Analysis of the specialized dentition of the bolosaurid parareptiles Bolosaurus from North America and Belebey from Russia, utilizing a combination of histological and tomographic data, reveals unusual patterns of tooth development and replacement. The data confirm that bolosaurid teeth have thecodont implantation with deep roots, the oldest known such example among amniotes, and independently evolved among much younger archosauromorphs (including dinosaurs and crocodilians) and among synapsids (including mammals). High-resolution CT scans were able to detect the density boundary between the alveolar bone and the jawbone, as confirmed by histology, and revealed the location and size of developing replacement teeth in the pulp cavity of functional teeth. Evidence provided by the paratype dentary of Belebey chengi indicates that replacement teeth are present along the whole tooth row at slightly different stages of development, with the ontogenetically more developed teeth anteriorly, suggesting that tooth replacement was highly synchronized. CT data also show tooth replacement is directly related to the presence of lingual pits in the jaw, and that migration of tooth buds occurs initially close to these resorption pits to a position immediately below the functional tooth within its pulp cavity. The size and complex shape of the replacement teeth in the holotype of Bolosaurus grandis indicate that the replacement teeth can develop within the pulp cavity to an advanced stage while the previous generation remains functional for an extended time, reminiscent of the condition seen in other amniotes with occluding dentitions, including mammals. PeerJ Inc. 2020-05-13 /pmc/articles/PMC7229766/ /pubmed/32440377 http://dx.doi.org/10.7717/peerj.9168 Text en ©2020 Snyder et al. https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.
spellingShingle Evolutionary Studies
Snyder, Adam J.
LeBlanc, Aaron R.H.
Jun, Chen
Bevitt, Joseph J.
Reisz, Robert R.
Thecodont tooth attachment and replacement in bolosaurid parareptiles
title Thecodont tooth attachment and replacement in bolosaurid parareptiles
title_full Thecodont tooth attachment and replacement in bolosaurid parareptiles
title_fullStr Thecodont tooth attachment and replacement in bolosaurid parareptiles
title_full_unstemmed Thecodont tooth attachment and replacement in bolosaurid parareptiles
title_short Thecodont tooth attachment and replacement in bolosaurid parareptiles
title_sort thecodont tooth attachment and replacement in bolosaurid parareptiles
topic Evolutionary Studies
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7229766/
https://www.ncbi.nlm.nih.gov/pubmed/32440377
http://dx.doi.org/10.7717/peerj.9168
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