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Reacquisition of the lower temporal bar in sexually dimorphic fossil lizards provides a rare case of convergent evolution

Temporal fenestration has long been considered a key character to understand relationships amongst reptiles. In particular, the absence of the lower temporal bar (LTB) is considered one of the defining features of squamates (lizards and snakes). In a re-assessment of the borioteiioid lizard Polyglyp...

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Autores principales: Simões, Tiago R., Funston, Gregory F., Vafaeian, Behzad, Nydam, Randall L., Doschak, Michael R., Caldwell, Michael W.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4829860/
https://www.ncbi.nlm.nih.gov/pubmed/27071447
http://dx.doi.org/10.1038/srep24087
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author Simões, Tiago R.
Funston, Gregory F.
Vafaeian, Behzad
Nydam, Randall L.
Doschak, Michael R.
Caldwell, Michael W.
author_facet Simões, Tiago R.
Funston, Gregory F.
Vafaeian, Behzad
Nydam, Randall L.
Doschak, Michael R.
Caldwell, Michael W.
author_sort Simões, Tiago R.
collection PubMed
description Temporal fenestration has long been considered a key character to understand relationships amongst reptiles. In particular, the absence of the lower temporal bar (LTB) is considered one of the defining features of squamates (lizards and snakes). In a re-assessment of the borioteiioid lizard Polyglyphanodon sternbergi (Cretaceous, North America), we detected a heretofore unrecognized ontogenetic series, sexual dimorphism (a rare instance for Mesozoic reptiles), and a complete LTB, a feature only recently recognized for another borioteiioid, Tianyusaurus zhengi (Cretaceous, China). A new phylogenetic analysis (with updates on a quarter of the scorings for P. sternbergi) indicates not only that the LTB was reacquired in squamates, but it happened independently at least twice. An analysis of the functional significance of the LTB using proxies indicates that, unlike for T. zhengi, this structure had no apparent functional advantage in P. sternbergi, and it is better explained as the result of structural constraint release. The observed canalization against a LTB in squamates was broken at some point in the evolution of borioteiioids, whereas never re-occuring in other squamate lineages. This case of convergent evolution involves a mix of both adaptationist and structuralist causes, which is unusual for both living and extinct vertebrates.
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spelling pubmed-48298602016-04-19 Reacquisition of the lower temporal bar in sexually dimorphic fossil lizards provides a rare case of convergent evolution Simões, Tiago R. Funston, Gregory F. Vafaeian, Behzad Nydam, Randall L. Doschak, Michael R. Caldwell, Michael W. Sci Rep Article Temporal fenestration has long been considered a key character to understand relationships amongst reptiles. In particular, the absence of the lower temporal bar (LTB) is considered one of the defining features of squamates (lizards and snakes). In a re-assessment of the borioteiioid lizard Polyglyphanodon sternbergi (Cretaceous, North America), we detected a heretofore unrecognized ontogenetic series, sexual dimorphism (a rare instance for Mesozoic reptiles), and a complete LTB, a feature only recently recognized for another borioteiioid, Tianyusaurus zhengi (Cretaceous, China). A new phylogenetic analysis (with updates on a quarter of the scorings for P. sternbergi) indicates not only that the LTB was reacquired in squamates, but it happened independently at least twice. An analysis of the functional significance of the LTB using proxies indicates that, unlike for T. zhengi, this structure had no apparent functional advantage in P. sternbergi, and it is better explained as the result of structural constraint release. The observed canalization against a LTB in squamates was broken at some point in the evolution of borioteiioids, whereas never re-occuring in other squamate lineages. This case of convergent evolution involves a mix of both adaptationist and structuralist causes, which is unusual for both living and extinct vertebrates. Nature Publishing Group 2016-04-13 /pmc/articles/PMC4829860/ /pubmed/27071447 http://dx.doi.org/10.1038/srep24087 Text en Copyright © 2016, Macmillan Publishers Limited http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
spellingShingle Article
Simões, Tiago R.
Funston, Gregory F.
Vafaeian, Behzad
Nydam, Randall L.
Doschak, Michael R.
Caldwell, Michael W.
Reacquisition of the lower temporal bar in sexually dimorphic fossil lizards provides a rare case of convergent evolution
title Reacquisition of the lower temporal bar in sexually dimorphic fossil lizards provides a rare case of convergent evolution
title_full Reacquisition of the lower temporal bar in sexually dimorphic fossil lizards provides a rare case of convergent evolution
title_fullStr Reacquisition of the lower temporal bar in sexually dimorphic fossil lizards provides a rare case of convergent evolution
title_full_unstemmed Reacquisition of the lower temporal bar in sexually dimorphic fossil lizards provides a rare case of convergent evolution
title_short Reacquisition of the lower temporal bar in sexually dimorphic fossil lizards provides a rare case of convergent evolution
title_sort reacquisition of the lower temporal bar in sexually dimorphic fossil lizards provides a rare case of convergent evolution
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4829860/
https://www.ncbi.nlm.nih.gov/pubmed/27071447
http://dx.doi.org/10.1038/srep24087
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