Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition

The teeth of sharks famously form a series of transversely organized files with a conveyor-belt replacement that are borne directly on the jaw cartilages, in contrast to the dermal plate-borne dentition of bony fishes that undergoes site-specific replacement. A major obstacle in understanding how th...

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Autores principales:	Richard P. Dearden, Sam Giles
Formato:	article
Lenguaje:	EN
Publicado:	The Royal Society 2021
Materias:	dentitions early vertebrates acanthodians chondrichthyans tooth evolution Palaeozoic Science Q
Acceso en línea:	https://doaj.org/article/979cd533b96d4bd0a21b642c812dec1e
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spelling	oai:doaj.org-article:979cd533b96d4bd0a21b642c812dec1e2021-11-10T10:31:48ZDiverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition10.1098/rsos.2108222054-5703https://doaj.org/article/979cd533b96d4bd0a21b642c812dec1e2021-11-01T00:00:00Zhttps://royalsocietypublishing.org/doi/10.1098/rsos.210822https://doaj.org/toc/2054-5703The teeth of sharks famously form a series of transversely organized files with a conveyor-belt replacement that are borne directly on the jaw cartilages, in contrast to the dermal plate-borne dentition of bony fishes that undergoes site-specific replacement. A major obstacle in understanding how this system evolved is the poorly understood relationships of the earliest chondrichthyans and the profusion of morphologically and terminologically diverse bones, cartilages, splints and whorls that they possess. Here, we use tomographic methods to investigate mandibular structures in several early branching ‘acanthodian’-grade stem-chondrichthyans. We show that the dentigerous jaw bones of disparate genera of ischnacanthids are united by a common construction, being growing bones with non-shedding dentition. Mandibular splints, which support the ventro-lateral edge of the Meckel's cartilage in some taxa, are formed from dermal bone and may be an acanthodid synapomorphy. We demonstrate that the teeth of Acanthodopsis are borne directly on the mandibular cartilage and that this taxon is deeply nested within an edentulous radiation, representing an unexpected independent origin of teeth. Many or even all of the range of unusual oral structures may be apomorphic, but they should nonetheless be considered when building hypotheses of tooth and jaw evolution, both in chondrichthyans and more broadly.Richard P. DeardenSam GilesThe Royal Societyarticledentitionsearly vertebratesacanthodianschondrichthyanstooth evolutionPalaeozoicScienceQENRoyal Society Open Science, Vol 8, Iss 11 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	dentitions early vertebrates acanthodians chondrichthyans tooth evolution Palaeozoic Science Q
spellingShingle	dentitions early vertebrates acanthodians chondrichthyans tooth evolution Palaeozoic Science Q Richard P. Dearden Sam Giles Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition
description	The teeth of sharks famously form a series of transversely organized files with a conveyor-belt replacement that are borne directly on the jaw cartilages, in contrast to the dermal plate-borne dentition of bony fishes that undergoes site-specific replacement. A major obstacle in understanding how this system evolved is the poorly understood relationships of the earliest chondrichthyans and the profusion of morphologically and terminologically diverse bones, cartilages, splints and whorls that they possess. Here, we use tomographic methods to investigate mandibular structures in several early branching ‘acanthodian’-grade stem-chondrichthyans. We show that the dentigerous jaw bones of disparate genera of ischnacanthids are united by a common construction, being growing bones with non-shedding dentition. Mandibular splints, which support the ventro-lateral edge of the Meckel's cartilage in some taxa, are formed from dermal bone and may be an acanthodid synapomorphy. We demonstrate that the teeth of Acanthodopsis are borne directly on the mandibular cartilage and that this taxon is deeply nested within an edentulous radiation, representing an unexpected independent origin of teeth. Many or even all of the range of unusual oral structures may be apomorphic, but they should nonetheless be considered when building hypotheses of tooth and jaw evolution, both in chondrichthyans and more broadly.
format	article
author	Richard P. Dearden Sam Giles
author_facet	Richard P. Dearden Sam Giles
author_sort	Richard P. Dearden
title	Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition
title_short	Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition
title_full	Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition
title_fullStr	Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition
title_full_unstemmed	Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition
title_sort	diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition
publisher	The Royal Society
publishDate	2021
url	https://doaj.org/article/979cd533b96d4bd0a21b642c812dec1e
work_keys_str_mv	AT richardpdearden diversestemchondrichthyanoralstructuresandevidenceforanindependentlyacquiredacanthodiddentition AT samgiles diversestemchondrichthyanoralstructuresandevidenceforanindependentlyacquiredacanthodiddentition
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Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition

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