Kurzfassung
Triassische Ichthyosaurier sind weit verbreitet und sehr vielgestaltig, aber die meisten Formen sind schlecht bekannt. Neue Funde, wie sie hier beschrieben werden, unterstreichen die erste Feststellung, lassen die zweite aber nur langsam ungültig werden.
Das erste assoziierte Skelett des ungewöhnlichen durophagen IchthyosauriersOmphalosaurus, O. wolfi aus der Mitteltrias (unterstes Ladin) der Salzburger Alpen, wird beschrieben und diskutiert. Die Wirbel haben die für Ichthyosaurier typische Morphologie und belegen damit eindeutig die Zugehörigkeit dieses Taxons zu den Ichthyosauriern.
Ein runder Knochen aus dem fränkischen Muschelkalk wird als linker Humérus vonOmphalosaurus sp. identifiziert. Diese beiden Funde weiten das Verbreitungsgebiet und das zeitliche Auftreten vonOmphalosaurus bedeutend aus, da die Gattung bis jetzt nur vom Westrand des nordamerikanischen Kratons und von Spitzbergen bekannt war. Die neuen Funde erlauben außerdem eine Differentialdiagnose der Gattung und eine Revision ihrer Arten, von denenOmphalosaurus nettarhynchus, O. nevadanus undO. wolfi als gültig erachtet werden, nicht aberO. nisseri.
Im Zusammenhang mit diesen neuen Einsichten zur Verbreitung triassischer Ichthyosaurier ist es nötig, die Gültigkeit schlecht bekannter Gattungen, z.B. des mitteltriassischenPessosaurus, zu überprüfen.Pessosaurus ist kein valides Taxon, weil ihm diagnostische Merkmale fehlen.
Wenn man den Fortschritt in der Erforschung der Trias-Ichthyosaurier bewertet, stellt man fest, daß die Diversität auf dem Gattungs- und Familienniveau weitgehend bekannt ist, zumindest was prä-norische Vorkommen in Nordamerika, Europa und Ostasien betrifft.
Abstract
Triassic ichthyosaurs are very widespread and diverse but most taxa are poorly known. New discoveries, such as described in this paper, underscore the first statement but only slowy invalidate the second.
The first associated skeleton of the unusual durophagous ichthyosaurOmphalosaurus (O. wolfi) is reported from the Middle Triassic (earliest Ladinian) of the northern Alps. The vertebrae are of the ichthyosaurian type, firmly establishing the ichthyosaurian affinities of the genus.
A round bone from the Muschelkalk of Franconia, Germany, is identified and described as a left humerus ofOmphalosaurus sp. These finds greatly extend the paleogeographic and temporal range ofOmphalosaurus which previously was only known from the western cratonic margin of North America and from Spitsbergen. The new records ofOmphalosaurus allow a revised differential diagnosis of the genus and a revision of its species. Valid species ofOmphalosaurus areO. nettarhynchus, O. nevadanus, andO. wolfi.
In conjunction with such new insights into Triassic ichthyosaur distribution, it is necessary to address the validity of the poorly known genera such as the Middle TriassicPessosaurus. This taxon must be considered invalid because it lacks diagnostic characters.
In assessing progress in research on Triassic ichthyosaurs and their paleobiogeography, it becomes apparent that supra-specific diversity appears largely known, at least for the pre-Norian record of North America, Europe, and East Asia.
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Sander, P.M., Faber, C. New finds ofOmphalosaurus and a review of Triassic ichthyosaur paleobiogeography. Paläontol Z 72, 149–162 (1998). https://doi.org/10.1007/BF02987823
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DOI: https://doi.org/10.1007/BF02987823