New findings in a 400 million-year-old Devonian placoderm shed light on jaw structure and function in basal gnathostomes

Abstract Arthodire placoderms have been proposed as the sister group of Chinese ‘maxillate’ placoderms plus all the more crownward gnathostomes. These basal groups provide key information for understanding the early evolution of jaws. Here, we test previous assumptions about placoderm jaw structure...

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Autores principales:	Yuzhi Hu, Jing Lu, Gavin C. Young
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/01ab1b64bc7c407bbe9f5f7bdfb0cf4c
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spelling	oai:doaj.org-article:01ab1b64bc7c407bbe9f5f7bdfb0cf4c2021-12-02T15:06:22ZNew findings in a 400 million-year-old Devonian placoderm shed light on jaw structure and function in basal gnathostomes10.1038/s41598-017-07674-y2045-2322https://doaj.org/article/01ab1b64bc7c407bbe9f5f7bdfb0cf4c2017-08-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-07674-yhttps://doaj.org/toc/2045-2322Abstract Arthodire placoderms have been proposed as the sister group of Chinese ‘maxillate’ placoderms plus all the more crownward gnathostomes. These basal groups provide key information for understanding the early evolution of jaws. Here, we test previous assumptions about placoderm jaw structure and function by using high-resolution computed tomography, digital dissection, and enlarged 3D printouts on a unique articulated 400 million-year-old buchanosteid arthrodire. The upper jaw has a double ethmoid and a palatobasal connection, but no otic connection; the dermal bone attachment for the quadrate is different to other placoderms. A separately ossified cartilage behind the mandibular joint is comparable to the interhyal of osteichthyans. Two articular facets on the braincase associated with the hyomandibular nerve foramen supported a possible epihyal element and a separate opercular cartilage. Reassembling and manipulating 3D printouts demonstrates the limits of jaw kenetics. The new evidence indicates unrecognized similarities in jaw structure between arthrodires and osteichthyans, and will help to clarify the sequence of character acquisition in the evolution of basal gnathostome groups. New details on the hyoid arch will help to reformulate characters that are key in the heated debate of placoderm monophyly or paraphyly.Yuzhi HuJing LuGavin C. YoungNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-12 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Yuzhi Hu Jing Lu Gavin C. Young New findings in a 400 million-year-old Devonian placoderm shed light on jaw structure and function in basal gnathostomes
description	Abstract Arthodire placoderms have been proposed as the sister group of Chinese ‘maxillate’ placoderms plus all the more crownward gnathostomes. These basal groups provide key information for understanding the early evolution of jaws. Here, we test previous assumptions about placoderm jaw structure and function by using high-resolution computed tomography, digital dissection, and enlarged 3D printouts on a unique articulated 400 million-year-old buchanosteid arthrodire. The upper jaw has a double ethmoid and a palatobasal connection, but no otic connection; the dermal bone attachment for the quadrate is different to other placoderms. A separately ossified cartilage behind the mandibular joint is comparable to the interhyal of osteichthyans. Two articular facets on the braincase associated with the hyomandibular nerve foramen supported a possible epihyal element and a separate opercular cartilage. Reassembling and manipulating 3D printouts demonstrates the limits of jaw kenetics. The new evidence indicates unrecognized similarities in jaw structure between arthrodires and osteichthyans, and will help to clarify the sequence of character acquisition in the evolution of basal gnathostome groups. New details on the hyoid arch will help to reformulate characters that are key in the heated debate of placoderm monophyly or paraphyly.
format	article
author	Yuzhi Hu Jing Lu Gavin C. Young
author_facet	Yuzhi Hu Jing Lu Gavin C. Young
author_sort	Yuzhi Hu
title	New findings in a 400 million-year-old Devonian placoderm shed light on jaw structure and function in basal gnathostomes
title_short	New findings in a 400 million-year-old Devonian placoderm shed light on jaw structure and function in basal gnathostomes
title_full	New findings in a 400 million-year-old Devonian placoderm shed light on jaw structure and function in basal gnathostomes
title_fullStr	New findings in a 400 million-year-old Devonian placoderm shed light on jaw structure and function in basal gnathostomes
title_full_unstemmed	New findings in a 400 million-year-old Devonian placoderm shed light on jaw structure and function in basal gnathostomes
title_sort	new findings in a 400 million-year-old devonian placoderm shed light on jaw structure and function in basal gnathostomes
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/01ab1b64bc7c407bbe9f5f7bdfb0cf4c
work_keys_str_mv	AT yuzhihu newfindingsina400millionyearolddevonianplacodermshedlightonjawstructureandfunctioninbasalgnathostomes AT jinglu newfindingsina400millionyearolddevonianplacodermshedlightonjawstructureandfunctioninbasalgnathostomes AT gavincyoung newfindingsina400millionyearolddevonianplacodermshedlightonjawstructureandfunctioninbasalgnathostomes
_version_	1718388428565905408

New findings in a 400 million-year-old Devonian placoderm shed light on jaw structure and function in basal gnathostomes

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