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A primitive actinopterygian braincase from the Tournaisian of Nova Scotia

The vertebrate fossil record of the earliest Carboniferous is notoriously poorly sampled, obscuring a critical interval in vertebrate evolution and diversity. Recent studies of diversity across the Devonian–Carboniferous boundary have proposed a vertebrate mass extinction at the end-Devonian, and re...

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Autores principales: Wilson, Conrad D., Pardo, Jason D., Anderson, Jason S. 
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society Publishing 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5990821/
https://www.ncbi.nlm.nih.gov/pubmed/29892368
http://dx.doi.org/10.1098/rsos.171727
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author Wilson, Conrad D.
Pardo, Jason D.
Anderson, Jason S. 
author_facet Wilson, Conrad D.
Pardo, Jason D.
Anderson, Jason S. 
author_sort Wilson, Conrad D.
collection PubMed
description The vertebrate fossil record of the earliest Carboniferous is notoriously poorly sampled, obscuring a critical interval in vertebrate evolution and diversity. Recent studies of diversity across the Devonian–Carboniferous boundary have proposed a vertebrate mass extinction at the end-Devonian, and recent phylogenies suggest that the origin of the actinopterygian crown may have occurred in the earliest Carboniferous, as part of a broader recovery fauna. However, the data necessary to test this are limited. Here, we describe a partial actinopterygian skull, including diagnostic elements of the posterior braincase, from the Tournaisian Horton Bluff Formation of Blue Beach, Nova Scotia. The braincase surprisingly shows a confluence of characters common in Devonian taxa but absent in Mississippian forms, such as an open spiracular groove; lateral dorsal aortae that pass through open broadly separated, parallel grooves in the ventral otoccipital region, posterior to the articulation of the first infrapharyngobranchial and an intertemporal–supratemporal complex. Phylogenetic analysis places it deep within the actinopterygian stem, among Devonian moythomasiids and mimiids, suggesting more phylogenetically inclusive survivorship of stem group actinopterygians across the end-Devonian mass extinction. With a high lineage survivorship in tetrapods and lungfish across the Devonian–Carboniferous boundary and high vertebrate diversity at Tournaisian localities, this hints at a more gradual turnover between Devonian and Carboniferous vertebrate faunas.
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spelling pubmed-59908212018-06-11 A primitive actinopterygian braincase from the Tournaisian of Nova Scotia Wilson, Conrad D. Pardo, Jason D. Anderson, Jason S.  R Soc Open Sci Biology (Whole Organism) The vertebrate fossil record of the earliest Carboniferous is notoriously poorly sampled, obscuring a critical interval in vertebrate evolution and diversity. Recent studies of diversity across the Devonian–Carboniferous boundary have proposed a vertebrate mass extinction at the end-Devonian, and recent phylogenies suggest that the origin of the actinopterygian crown may have occurred in the earliest Carboniferous, as part of a broader recovery fauna. However, the data necessary to test this are limited. Here, we describe a partial actinopterygian skull, including diagnostic elements of the posterior braincase, from the Tournaisian Horton Bluff Formation of Blue Beach, Nova Scotia. The braincase surprisingly shows a confluence of characters common in Devonian taxa but absent in Mississippian forms, such as an open spiracular groove; lateral dorsal aortae that pass through open broadly separated, parallel grooves in the ventral otoccipital region, posterior to the articulation of the first infrapharyngobranchial and an intertemporal–supratemporal complex. Phylogenetic analysis places it deep within the actinopterygian stem, among Devonian moythomasiids and mimiids, suggesting more phylogenetically inclusive survivorship of stem group actinopterygians across the end-Devonian mass extinction. With a high lineage survivorship in tetrapods and lungfish across the Devonian–Carboniferous boundary and high vertebrate diversity at Tournaisian localities, this hints at a more gradual turnover between Devonian and Carboniferous vertebrate faunas. The Royal Society Publishing 2018-05-16 /pmc/articles/PMC5990821/ /pubmed/29892368 http://dx.doi.org/10.1098/rsos.171727 Text en © 2018 The Authors. http://creativecommons.org/licenses/by/4.0/ Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.
spellingShingle Biology (Whole Organism)
Wilson, Conrad D.
Pardo, Jason D.
Anderson, Jason S. 
A primitive actinopterygian braincase from the Tournaisian of Nova Scotia
title A primitive actinopterygian braincase from the Tournaisian of Nova Scotia
title_full A primitive actinopterygian braincase from the Tournaisian of Nova Scotia
title_fullStr A primitive actinopterygian braincase from the Tournaisian of Nova Scotia
title_full_unstemmed A primitive actinopterygian braincase from the Tournaisian of Nova Scotia
title_short A primitive actinopterygian braincase from the Tournaisian of Nova Scotia
title_sort primitive actinopterygian braincase from the tournaisian of nova scotia
topic Biology (Whole Organism)
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5990821/
https://www.ncbi.nlm.nih.gov/pubmed/29892368
http://dx.doi.org/10.1098/rsos.171727
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