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Internal cranial anatomy of Early Triassic species of †saurichthys (Actinopterygii: †saurichthyiformes): implications for the phylogenetic placement of †saurichthyiforms

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dc.contributor.author Argyriou T.
dc.contributor.author Giles S.
dc.contributor.author Friedman M.
dc.contributor.author Romano C.
dc.contributor.author Kogan I.
dc.contributor.author Sánchez-Villagra M.
dc.date.accessioned 2019-01-22T20:53:16Z
dc.date.available 2019-01-22T20:53:16Z
dc.date.issued 2018
dc.identifier.uri https://dspace.kpfu.ru/xmlui/handle/net/149264
dc.description.abstract © 2018 The Author(s). Background: †Saurichthyiformes were a successful group of latest Permian-Middle Jurassic predatory actinopterygian fishes and constituted important, widely-distributed components of Triassic marine and freshwater faunas. Their systematic affinities have long been debated, with †saurichthyiforms often being aligned with chondrosteans, a group today comprising sturgeons and paddlefishes. However, their character-rich endocranial anatomy has not been investigated in detail since the first half of the 20th century. Since then, major advances have occurred in terms of our understanding of early actinopterygian anatomy, as well as techniques for extracting morphological data from fossils. Results: We used μCT to study the internal cranial anatomy of two of the stratigraphically oldest representatives of †Saurichthys, from the Early Triassic of East Greenland and Nepal. Our work revealed numerous previously unknown characters (e.g., cryptic oticooccipital fissure; intramural diverticula of braincase; nasobasal canals; lateral cranial canal; fused dermohyal), and permitted the reevalution of features relating to the structure of cranial fossae, basicranial circulation and opercular anatomy of the genus. Critically, we reinterpret the former †saurichthyiform opercle as an expanded subopercle. For comparison, we also produced the first digital models of a braincase and endocast of a sturgeon (A. brevirostrum). New information from these taxa was included in a broad phylogenetic analysis of Actinopterygii. †Saurichthyiforms are resolved as close relatives of †Birgeria, forming a clade that constitutes the immediate sister group of crown actinopterygians. However, these and other divergences near the actinopterygian crown node are weakly supported. Conclusions: Our phylogeny disagrees with the historically prevalent hypothesis favoring the chondrostean affinities of †saurichthyiforms. Previously-proposed synapomorphies uniting the two clades, such as the closure of the oticooccipital fissure, the posterior extension of the parasphenoid, and the absence of an opercular process, are all widespread amongst actinopterygians. Others, like those relating to basicranial circulation, are found to be based on erroneous interpretations. Our work renders the †saurichthyiform character complex adequately understood, and permits detailed comparisons with other stem and crown actinopterygians. Our phylogenetic scheme highlights outstanding questions concerning the affinity of many early actinopterygians, such as the Paleozoic-early Mesozoic deep-bodied forms, which are largely caused by lack of endoskeletal data.
dc.subject Acipenser
dc.subject Actinopterygii
dc.subject Chondrostei
dc.subject Cranial fossae
dc.subject East Greenland
dc.subject Microtomography (μCT)
dc.subject Nepal
dc.subject Phylogeny
dc.subject Triassic
dc.subject †Saurichthys
dc.title Internal cranial anatomy of Early Triassic species of †saurichthys (Actinopterygii: †saurichthyiformes): implications for the phylogenetic placement of †saurichthyiforms
dc.type Article
dc.relation.ispartofseries-issue 1
dc.relation.ispartofseries-volume 18
dc.collection Публикации сотрудников КФУ
dc.source.id SCOPUS-2018-18-1-SID85055827247

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  • Публикации сотрудников КФУ Scopus [22633]
    Коллекция содержит публикации сотрудников Казанского федерального (до 2010 года Казанского государственного) университета, проиндексированные в БД Scopus, начиная с 1970г.

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