Molar occlusion and jaw roll in early crown mammals

Abstract Triconodontidae are considered the first carnivorous crown mammals. A virtual reconstruction of the masticatory cycle in the Late Jurassic Priacodon showed that triconodontid dental function is characterized by precise cutting on elongated crests. The combination of traits linked to both ca...

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Autores principales:	Kai R. K. Jäger, Richard L. Cifelli, Thomas Martin
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2020
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/6dc4a63671124375b97fd329745bdf1c
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spelling	oai:doaj.org-article:6dc4a63671124375b97fd329745bdf1c2021-12-02T11:59:40ZMolar occlusion and jaw roll in early crown mammals10.1038/s41598-020-79159-42045-2322https://doaj.org/article/6dc4a63671124375b97fd329745bdf1c2020-12-01T00:00:00Zhttps://doi.org/10.1038/s41598-020-79159-4https://doaj.org/toc/2045-2322Abstract Triconodontidae are considered the first carnivorous crown mammals. A virtual reconstruction of the masticatory cycle in the Late Jurassic Priacodon showed that triconodontid dental function is characterized by precise cutting on elongated crests. The combination of traits linked to both carnivorous diets (e.g. fore-aft cutting edges) and insectivorous diets (transverse crests and lobes) suggests a varied faunivorous diet appropriate to the small body size of most triconodontids. Total length of molar shear decreased with wear, suggesting a dietary shift during ontogeny. Embrasure occlusion is confirmed for P. fruitaensis as indicated by premolar positioning, facet orientation, and collision areas. Embrasure occlusion is considered a general feature of all Eutriconodonta, whereas the previously assumed Morganucodon-like pattern is limited to few early mammaliaforms. Unlike modern carnivores, significant roll of around 10° of the active hemimandible occurred during the power stroke. Roll was likely passive in Triconodontidae in contrast to active roll described for extant therians. The triconodontid molar series was highly uniform and adapted to a precise fit, with self-sharpening lower molar cusps. Whereas the uniformity ensured good cutting capabilities, it likely put the dentition under greater constraints, conserving the highly stereotyped nature of triconodontid molars for 60–85 Ma.Kai R. K. JägerRichard L. CifelliThomas MartinNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 10, Iss 1, Pp 1-12 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Kai R. K. Jäger Richard L. Cifelli Thomas Martin Molar occlusion and jaw roll in early crown mammals
description	Abstract Triconodontidae are considered the first carnivorous crown mammals. A virtual reconstruction of the masticatory cycle in the Late Jurassic Priacodon showed that triconodontid dental function is characterized by precise cutting on elongated crests. The combination of traits linked to both carnivorous diets (e.g. fore-aft cutting edges) and insectivorous diets (transverse crests and lobes) suggests a varied faunivorous diet appropriate to the small body size of most triconodontids. Total length of molar shear decreased with wear, suggesting a dietary shift during ontogeny. Embrasure occlusion is confirmed for P. fruitaensis as indicated by premolar positioning, facet orientation, and collision areas. Embrasure occlusion is considered a general feature of all Eutriconodonta, whereas the previously assumed Morganucodon-like pattern is limited to few early mammaliaforms. Unlike modern carnivores, significant roll of around 10° of the active hemimandible occurred during the power stroke. Roll was likely passive in Triconodontidae in contrast to active roll described for extant therians. The triconodontid molar series was highly uniform and adapted to a precise fit, with self-sharpening lower molar cusps. Whereas the uniformity ensured good cutting capabilities, it likely put the dentition under greater constraints, conserving the highly stereotyped nature of triconodontid molars for 60–85 Ma.
format	article
author	Kai R. K. Jäger Richard L. Cifelli Thomas Martin
author_facet	Kai R. K. Jäger Richard L. Cifelli Thomas Martin
author_sort	Kai R. K. Jäger
title	Molar occlusion and jaw roll in early crown mammals
title_short	Molar occlusion and jaw roll in early crown mammals
title_full	Molar occlusion and jaw roll in early crown mammals
title_fullStr	Molar occlusion and jaw roll in early crown mammals
title_full_unstemmed	Molar occlusion and jaw roll in early crown mammals
title_sort	molar occlusion and jaw roll in early crown mammals
publisher	Nature Portfolio
publishDate	2020
url	https://doaj.org/article/6dc4a63671124375b97fd329745bdf1c
work_keys_str_mv	AT kairkjager molarocclusionandjawrollinearlycrownmammals AT richardlcifelli molarocclusionandjawrollinearlycrownmammals AT thomasmartin molarocclusionandjawrollinearlycrownmammals
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Molar occlusion and jaw roll in early crown mammals

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