The dentary of hadrosauroid dinosaurs: evolution through heterochrony
Söderblom, Fredrik (Uppsala University. Department of Earth Sciences)
Blanco, Alejandro (Bayerische Staatssammlung für Paläontologie und Geologie)
Prieto-Marquez, Albert (Institut Català de Paleontologia Miquel Crusafont)
Campione, Nicolas (Uppsala University. Department of Earth Sciences)

Data:	2023
Resum:	The near-global distribution of hadrosaurid dinosaurs during the Cretaceous has been attributed to mastication, a behaviour commonly recognized as a mammalian adaptation. Its occurrence in a non-mammalian lineage should be accompanied by the evolution of several morphological modifications associated with food acquisition and processing. This study investigated morphological variation in the dentary, a major element of the hadrosauroid lower jaw. Eighty-four hadrosauroid dentaries were subjected to geometric morphometric and statistical analyses to investigate their taxonomic, ontogenetic, and individual variation. Results suggest increased food acquisition and processing efficiency in saurolophids through a complex pattern of evolutionary and growth-related changes. The edentulous region grew longer relative to dentary length, allowing for food acquisition specialization anteriorly and processing posteriorly, and became ventrally directed, possibly associated with foraging low-growing vegetation, especially in younger individuals. The saurolophid coronoid process became anteriorly directed and relatively more elongate, with an expanded apex, increasing moment arm length, with muscles pulling the jaw more posteriorly, increasing mechanical advantage. During growth, all hadrosauroids underwent anteroposterior dental battery elongation by the addition of teeth, and edentulous region ventralization decreased. The dental battery became deeper in saurolophids by increasing the number of teeth per tooth family. The increased coronoid process anterior inclination and relative edentulous region elongation in saurolophids are hypothesized to have evolved through hypermorphosis and/or acceleration, peramorphic heterochronic processes; the development of an anteroposteriorly shorter but dorsoventrally taller saurolophid dentary, is probably due to post-displacement in dental battery elongation and edentulous region decreased ventral orientation, a paedomorphic heterochronic process.
Ajuts:	Agencia Estatal de Investigación RYC2021-034269-I Agencia Estatal de Investigación PID2020-119811GB-I00 Ministerio de Economía y Competitividad RYC-2015-17388
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Hadrosaur ; Dentary ; Geometric morphometrics ; Heterochrony ; Paedomorphosis ; Peramorphosis
Publicat a:	Palaeontology, Vol. 66, issue 5 (Sep.-Oct. 2023) , ISSN 1475-4983

DOI: 10.1111/pala.12674

31 p, 3.6 MB

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