Hostname: page-component-78c5997874-t5tsf Total loading time: 0 Render date: 2024-11-19T14:37:35.163Z Has data issue: false hasContentIssue false
  • English
  • Français

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,
Get access Rights & Permissions [Opens in a new window]

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 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bassani, F. 1886. Sui fossili e sull'età degli schisti bituminosi triasici di Besano in Lombardia.—Communicazione preliminare. Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale, 29:15–17.Google Scholar
Baur, G. 1887. Ueber den Ursprung der Extremitäten der Ichthyopterygia. Berichte über die Versammlungen des Oberrheinischen geologischen Vereines, 20:17–20.Google Scholar
Beer, G. R. de. 1937. The Development of the Vertebrate Skull. Clarendon Press, Oxford, 552 p.Google Scholar
Besmer, A. 1947. Beiträge zur Kenntnis des Ichthyosauriergebisses. Schweizerische Palaeontologische Abhandlungen, 65:1–21.Google Scholar
Blainville, H. M. D. de. 1835. Description de quelques espéces de reptiles de la Californie. Nouvelles Annales du Muséum d'Histoire Naturelle, Paris, 4:233–296.Google Scholar
Brinkmann, W. 1998. Sangiorgiosaurus n. g.—eine neue Mixosaurier-Gattung (Mixosauridae, Ichthyosauria) mit Quetschzähnen aus der Grenzbitumenzone (Mitteltrias) des Monte San Giorgio (Schweiz, Kanton Tessin). Neues Jahrbuch für Geologie und Paläontologie Abhandlungen, 207:125–144.CrossRefGoogle Scholar
Callaway, J. M. 1989. Systematics, phylogeny, and ancestry of Triassic ichthyosaurs. Unpublished , University of Rochester, Rochester, 204 p.Google Scholar
Callaway, J. M. 1997. A new look at Mixosaurus. p. 45–59. In Callaway, J. M. and Nicholls, E. L. (eds.), Ancient Marine Reptiles. Academic Press, London and New York.CrossRefGoogle Scholar
Dalrymple, G. H. 1979. On the jaw mechanism of the snail-crushing lizards, Dracaena Daudin 1802 (Reptilia, Lacertilia, Teiidae). Journal of Herpetology, 13:303–311.CrossRefGoogle Scholar
Dames, W. von. 1895. Über die Ichthyopterygier der Triasformation. Sitzungsberichte der Königlich-preussischen Akademie der Wissenschaften, Berlin, 46:1045–1050.Google Scholar
Estes, R., de Queiroz, K., and Gauthier, J. 1988. Phylogenetic relationships within Squamata. p. 119–281. In Estes, R. and Pregill, G. (eds.), Phylogenetic Relationships of the Lizard Families. Stanford University Press, Stanford, 631 p.Google Scholar
Edinger, T. von. 1934. Mixosaurus-Schädelrest aus Rüdersdorf. Jahrbuch der Preußischen Geologischen Landesanstalt, 55:341–347.Google Scholar
Evans, S. E., and Haubold, H. 1987. A review of the Upper Permian genera Coelurosauravus, Weigeltisaurus, and Gracilisaurus (Reptilia: Diapsida). Zoological Journal of the Linnean Society, 90:275–303.CrossRefGoogle Scholar
Fraas, E. 1891. Ichthyosaurier der Süddeutschen Trias- und Jura- Ablagerungen. Verlag der H. Laupp'schen Buchhandlung, Tübingen, 81 p.Google Scholar
Godefroit, P. 1993. The skull of Stenopterygius longifrons (Owen, 1881). Revue de Paléobiologie, Genève, Volume Spéciale, 7:67–84.Google Scholar
Huene, F. von. 1916. Beiträge zur Kenntnis der Ichthyosaurier im deutschen Muschelkalk. Palaeontographica, 62:1–68.Google Scholar
Huene, F. von. 1925. Einige Beobachtungen an Mixosaurus cornalianus (Bassani). Centralblatt für Mineralogie, Geologie, und Paläontologie, B, 9:289–295.Google Scholar
Huene, F. von. 1935. Neue Beobachtungen an Mixosaurus. Palaeontologische Zeitschrift, 17:159–162.CrossRefGoogle Scholar
Hulke, J. W. 1873. Memorandum on some fossil vertebrate remains collected by the Swedish expedition to Spitzbergen in 1864 and 1868. Bihang till K. Svenska Vetenskapskademiens Handlinger, 1, Afdelning IV, 9:1–11.Google Scholar
Kirton, A. M. 1983. A review of British Upper Jurassic ichthyosaurs. Unpublished , University of Newcastle, 239 p.Google Scholar
Maddison, W. P., and Maddison, D. R. 1992. MacClade: Analysis of phylogeny and character evolution. Version 3.0. Sinauer Associates, Sunderland, Massachusetts.Google Scholar
Maisch, M. W. 1997. A case against a diapsid origin of the Ichthyosauria. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 205:111–127.CrossRefGoogle Scholar
Maisch, M. W., and Matzke, A. T. 1997. Observations on Triassic ichthyosaurs. Part I: Structure of the palate and mode of tooth implantation in Mixosaurus cornalianus (Bassani, 1886). Neues Jahrbuch für Geologie und Paläontologie, Monatshefte, 1997:717–732.CrossRefGoogle Scholar
Maisch, M. W., and Matzke, A. T. 1998. Observation on Triassic ichthyosaurs. Part III: A crested predatory mixosaurid from the Middle Triassic of the Germanic Basin. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 209:105–134.CrossRefGoogle Scholar
Massare, J. A. 1987. Tooth morphology and prey preference of Mesozoic marine reptiles. Journal of Vertebrate Paleontology, 7:121–137.CrossRefGoogle Scholar
Massare, J. A., and Callaway, J. M. 1990. The affinities and ecology of Triassic ichthyosaurs. Geological Society of America Bulletin, 102:409–416.2.3.CO;2>CrossRefGoogle Scholar
Mazin, J.-M. 1981. Grippia longirostris Wiman, 1929, un Ichthyopterygia primitif du Trias inférieur du Spitsberg. Bulletin du Muséum National d'Histoire Naturelle, 4:317–340.Google Scholar
McGowan, C. 1969. The cranial morphology and interrelationships of the Lower Liassic ichthyosaurs. Unpublished Ph.D. dissertation, University of London, 498 p.Google Scholar
McGowan, C. 1973. The cranial morphology of the Lower Liassic Latipinnate ichthyosaurs of England. Bulletin of the British Museum (Natural History), Geology, 24:1–109.CrossRefGoogle Scholar
Merriam, J. C. 1908. Triassic Ichthyosauria, with special reference to the American forms. Memoirs of the University of California, 1:1–196.Google Scholar
Merriam, J. C. 1910. The skull and dentition of a primitive ichthyosaurian from the Middle Triassic. University of California Publications, Bulletin of the Department of Geology, 5:381–390.Google Scholar
Motani, R. 1996. Redescription of the dental features of an Early Triassic ichthyosaur Utatsusaurus hataii. Journal of Vertebrate Paleontology, 16:396–402.CrossRefGoogle Scholar
Motani, R. 1997a. Phylogeny of the Ichthyosauria (Amniota: Reptilia) with special reference to Triassic forms. Unpublished Ph.D. dissertation, University of Toronto, 384 p.Google Scholar
Motani, R. 1997b. Temporal and spatial distribution of tooth implantation in ichthyosaurs. p. 81–103. In Callaway, J. M. and Nicholls, E. L. (eds.), Ancient Marine Reptiles. Academic Press, London and New York.CrossRefGoogle Scholar
Motani, R. 1997c. Redescription of the dentition of Grippia longirostris (Ichthyosauria) with a comparison with Utatsusaurus hataii. Journal of Vertebrate Paleontology, 17:39–44.CrossRefGoogle Scholar
Motani, R. 1998. First complete forefin of the ichthyosaur Grippia longirostris discovered from the Triassic of Spitsbergen. Palaeontology, 41:591–600.Google Scholar
Motani, R. 1999. On the evolution and homology of ichthyosaurian forefins. Journal of Vertebrate Paleontology, 19:28–41.CrossRefGoogle Scholar
Motani, R.In press. Phylogeny of the Ichthyopterygia. Journal of Vertebrate Paleontology.Google Scholar
Motani, R., Minoura, N., and Ando, T. 1998. Ichthyosaurian relationships illuminated by new primitive skeletons from Japan. Nature, 393:255–257.CrossRefGoogle Scholar
Motani, R., You, H., and McGowan, C. 1996. Eel-like swimming in the earliest ichthyosaurs. Nature, 382:347–348.CrossRefGoogle Scholar
Nicholls, E. L., and Brinkman, D. B. 1995. A new ichthyosaur from the Triassic of Sulphur Mountain Formation of British Columbia, p. 521–535. In Sarjeant, W. A. S. (ed.), Vertebrate Fossils and the Evolution of Scientific Concepts. Gordon and Breach, Amsterdam.Google Scholar
Nicholls, E. L., Brinkman, D. B., and Callaway, J. M.In press. New material of Phalarodon (Reptilia, Ichthyosauria) from the Triassic of British Columbia and its bearing on the interrelationships of mixosaurs. Palaeontographica.Google Scholar
Osborn, H. F. 1903. The reptilian subclass Diapsida and Synapsida and the early history of the Diaptosauria. Memoirs of the American Museum of Natural History, 1:449–507.Google Scholar
Owen, R. 1840. Report on British fossil reptiles. Report of the British Association for the Advancement of Science, 9:43–126.Google Scholar
Owen, R. 1881. A Monograph of the Fossil Reptilia of the Liassic Formations. Part III, Ichthyopterygia, p. 81–134. Palaeontological Society. London. 134 p.Google Scholar
Quenstedt, F. A. 1852. Handbuch der Petrefactenkunde. Tübingen. 792 p.Google Scholar
Repossi, E. 1902. Il mixosauro degli strati triasici di Besano in Lombardia. Atti della Società Italiana di Scienze Naturali, 41:61–72.Google Scholar
Ride, W. D. L., Sabrosky, C. W., Bernardi, G., Melville, R. V., Corliss, J. O., Forest, J., Key, K. H. L., and Wright, C. W. 1985. International Code of Zoological Nomenclature (third edition). International Trust for Zoological Nomenclature, 338 p. Also see ICZN web page (http://www.iczn.org/iczn.htm).Google Scholar
Rieppel, O. 1992. Studies on skeleton formation in reptiles. III. Patterns of ossification in the skeleton of Lacerta vivipara Jacquin (Reptilia, Squamata). Fieldiana Zoology, New Series, 68:1–25.Google Scholar
Romer, A. S. 1968. An ichthyosaur skull from the Cretaceous of Wyoming. Contributions to Geology, University of Wyoming, 7:27–41.Google Scholar
Sollas, W. J. 1916. The skull of Ichthyosaurus studied in serial sections. Philosophical Transactions of the Royal Society of London, Series B, 208:63–126.Google Scholar
Sues, H.-D., Shubin, N. H., and Olsen, P. E. 1994. A new sphenodontian (Lepidosauria: Rhynchocephalia) from the Mccoy Brook Formation (Lower Jurassic) of Nova Scotia, Canada. Journal of Vertebrate Paleontology, 14:327–340.CrossRefGoogle Scholar
Swofford, D. L. 1998. PAUP*. Phylogenetic Analysis Using Parsimony (*and Other Methods. Version 4). Sinauer Associates, Sunderland, Massachusetts.Google Scholar
Wiman, C. 1910. Ichthyosaurier aus der Trias Spitzbergens. Bulletin of the Geological Institution of the University of Upsala, 10:124–148.Google Scholar
Wiman, C. 1912. Über Mixosaurus cornalianus Bass. sp. Bulletin of the Geological Institution of the University of Upsala, 11:230–241.Google Scholar