{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T22:22:44Z","timestamp":1788387764982,"version":"build-2803163510"},"reference-count":49,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2021,12,5]],"date-time":"2021-12-05T00:00:00Z","timestamp":1638662400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/501100008345","name":"Fujiwara Natural History Foundation","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100008345","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Journal of Anatomy"],"published-print":{"date-parts":[[2022,5]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>The extinct freshwater choristoderan reptiles <jats:italic>Champsosaurus<\/jats:italic> and <jats:italic>Simoedosaurus<\/jats:italic> are characterised by large body size and an elongated snout. They have often been considered as eco\u2010analogues of crocodilians based on superficial similarities. The slender\u2010snouted <jats:italic>Champsosaurus<\/jats:italic> has been described as a \u2018gavial\u2010like reptile\u2019, which implies it feeds underwater with a lateral swipe of the head and neck, as in the living slender\u2010snouted crocodilians such as <jats:italic>Gavialis gangeticus<\/jats:italic>. In contrast, the short\u2010snouted <jats:italic>Simoedosaurus<\/jats:italic> is often compared with short\u2010snouted living crocodilians and is considered to take single prey items. However, the neck mobility and flexibility needed for feeding movements are poorly understood even in extant crocodilians. This study explores the relationship between cervical morphology and neck flexion, focusing particularly on lateral and dorsal movements in <jats:italic>G<\/jats:italic>. <jats:italic>gangeticus<\/jats:italic> by comparison with shorter\u2010snouted crocodilians. The paper also describes a method to estimate the maximum angle of neck dorsiflexion in choristoderes based on the cervical morphology of extant crocodilian species. Three indices were used in this study, of which Index 3 is newly proposed, to compare cervical morphology and intervertebral joint flexibility: (1) Enclosed zygapophyseal angles (EZA) as an index of dorsoventral\/ bilateral flexibility, (2) moment arm (M) of dorsiflexor muscles as an Index of resistance against ventroflexion and (3) the orientations of zygapophysial facets for a maximum angle of dorsiflexion. These Indices were validated using \u00b5CT scanning of fresh specimens of <jats:italic>G<\/jats:italic>. <jats:italic>gangeticus<\/jats:italic> and <jats:italic>Caiman latirostris<\/jats:italic> in lateral and dorsal flexion. A unique mechanism of lateral flexion was identified in <jats:italic>G. gangeticus<\/jats:italic> that uses a combination of the following features: (1) lateral flexion mainly restricted to the anterior cervical vertebrae (v2\/v3: high EZA, with more horizontal zygapophyses) and (2) high degree of dorsiflexion at the v3\/v4 and v4\/v5 joints with potential for dorsal flexibility through the middle\u2010posterior neck, which is used in inertial feeding. In contrast, <jats:italic>Champsosaurus<\/jats:italic> and <jats:italic>Simoedosaurus<\/jats:italic> possess relatively short cervical vertebrae, as in short\u2010snouted crocodilians. The middle\u2010posterior cervical vertebrae of <jats:italic>Champsosaurus<\/jats:italic> are specialised for lateral flexion (high EZA), and there is only limited capacity for dorsiflexion throughout the neck. Like <jats:italic>G. gangeticus<\/jats:italic>, therefore, <jats:italic>Champsosaurus<\/jats:italic> may have used its slender snout to grab fish from shoals using lateral sweeping motions of the head and neck, but the movement is through the neck, not the craniocervical joint. However, inertial feeding is less likely to have occurred in this genus, and the aligned palatal dentition may have aided the lingual transport of prey into the mouth. <jats:italic>Simoedosaurus<\/jats:italic>, on the other hand, appears to have been less specialised, with a neck that combined lateral and dorsolateral flexion, a move that could have been effective in catching both terrestrial and aquatic prey. Where these two choristoderan genera occurred in the same place, they may have divided their niche by prey types.<\/jats:p>","DOI":"10.1111\/joa.13600","type":"journal-article","created":{"date-parts":[[2021,12,5]],"date-time":"2021-12-05T09:31:22Z","timestamp":1638696682000},"page":"893-913","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Feeding behaviour and functional morphology of the neck in the long\u2010snouted aquatic fossil reptile <i>Champsosaurus<\/i> (Reptilia: Diapsida) in comparison with the modern crocodilian <i>Gavialis gangeticus<\/i>"],"prefix":"10.1111","volume":"240","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0334-7259","authenticated-orcid":false,"given":"Ryoko","family":"Matsumoto","sequence":"first","affiliation":[{"name":"Kanagawa Prefectural Museum of Natural History  Odawara Kanagawa Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9393-5734","authenticated-orcid":false,"given":"Shin\u2010ichi","family":"Fujiwara","sequence":"additional","affiliation":[{"name":"The Nagoya University Museum  Nagoya Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0799-4154","authenticated-orcid":false,"given":"Susan E.","family":"Evans","sequence":"additional","affiliation":[{"name":"Centre for Integrative Anatomy Department of Cell and Developmental Biology UCL University College London  London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2021,12,5]]},"reference":[{"key":"e_1_2_11_2_1","first-page":"63","article-title":"The occurrence and ingestion of gastroliths in two captive crocodilians","volume":"25","author":"Brazaitis 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