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The skull and taxonomy of Mixosaurus (Ichthyopterygia)

Published online by Cambridge University Press:  14 July 2015

Ryosuke Motani
Ryosuke Motani*
Affiliation:
University of California, Museum of Paleontology, 1101 Valley Life Sciences Building, Berkeley, CA 94720-4780,
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Abstract

Mixosaurus, a Middle Triassic ichthyopterygian, has traditionally been recognized as a typically primitive ichthyopterygian, but this view was recently questioned. Examination of the skull of Mixosaurus revealed many features to confirm this doubt. Its cranial characters, such as the parietal ridge and short supratemporal process of the parietal, are shared with derived ichthyopterygians from the Jurassic. Mixosaurus also has features that are derived within the Ichthyopterygia and unique to the genus, such as a long sagittal crest reaching the nasal, and an expanded anterior terrace of the upper temporal fenestra that also reaches the nasal. Phalarodon, Contectopalatus, and Sangiorgiosaurus are all considered as junior synonyms of Mixosaurus. The supratemporal, squamosal, and quadratojugal are all present in Mixosaurus atavus, as in basal ichthyopterygians. Because all basal ichthyopterygians, and even some derived ichthyopterygians from the Jurassic, have these three elements, the absence of the squamosal in Ichthyosaurus and Platypterygius should be considered derived if it is not preservational.

Type
Research Article
Information
Journal of Paleontology , Volume 73 , Issue 5 , September 1999 , pp. 924 - 935
Copyright
Copyright © The Paleontological Society 

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