Eurhinosaurus

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Eurhinosaurus
Eurhinosaurus longirostris in the State Museum for Natural History in Stuttgart

Eurhinosaurus longirostris in the State Museum for Natural History in Stuttgart

Temporal occurrence
Lower Jurassic ( Toarcium )
182.7 to 174.1 million years
Locations
Systematics
Land vertebrates (Tetrapoda)
Sauropsida
Diapsida
Ichthyosaur (Ichthyosauria)
Leptonectidae
Eurhinosaurus
Scientific name
Eurhinosaurus
Abel , 1909
species
  • Eurhinosaurus longirostris Owen & Jaeger in von Jaeger, 1856

Eurhinosaurus ( Greek f1 for "good-nosed lizard" from εὖ eu "good", ῥίς rhis [ Gen. ῥινός rhinos ] "nose" and σαῦρος sauros "lizard") is an extinct medium-sized ichthyosaur genus of the Lower Jurassic ( Toarcium ) of Europe ( England , Germany , Benelux , France , Austria and Switzerland ). Eurhinosaurus appears for the first time in the Lower Toarcian and can be detected for the last time in the Middle Toarcian, i.e. lived around 180 million years ago. Its length varies greatly and is specified to be over 6 m, but most specimens are between 3 and 5 meters in length. In this genus only the species Eurhinosaurus longirostris is known. A second species, Eurhinosaurus costini , was only briefly assigned to this genus and is now considered the only species in the genus Excalibosaurus .

Eurhinosaurus longirostris from Schandelah (Lower Saxony), in the GeoPark information center in Königslutter

features

The extreme overbite is characteristic of the Eurhinosaurus genus . The lower jaw is about 60% shorter than the upper jaw. Furthermore, the very elongated and narrow front fins are an easily recognizable feature. The also narrow hind fins reach more than two thirds of the front fin length. The synapomorphies also include the square jugal in the posterior position and smooth, pointed, narrow teeth. The eye socket is remarkably large and round, and it is the reason for the greatly reduced cheek region. The supratemporal windows (upper temple windows) are extremely small, the supratemporal bone is very large, broad when viewed from above and extends to the edge of the eye sockets. In the lower caudal fin lobe, the spine was less bent downward than in many other ichthyosaur species. The angle was probably only about 33–45 °. The chevron bones are cartilaginous.

Live reconstruction of the Eurhinosaurus . The elongated upper jaw is clearly visible

Paleobiology

Much has been speculated about the way of life of Eurhinosaurus . Friedrich von Huene already took the view that the long snout was used to impale prey. The branching ducts that appear on the upper jaw would represent blood ducts that would accelerate the healing of this sensitive body part. McGowan believes that Eurhinosaurus injured its prey by moving its teeth quickly up and down and then ate it. Riess (1986), on the other hand, assumes more soil-related feeding behavior. The ramifications in the front area of ​​the snout would represent a sensory organ that Eurhinosaurus would have used to track down its prey in the sediment.

Front view of the skulls of Eurhinosaurus longirostris (above) and Temnodontosaurus trigonodon (below) in the State Museum of Natural History in Stuttgart

Paleoecology

Eurhinosaurus lived in a shallow sea with depths up to 100 m. At that time the Tethys had a rich fauna of cephalopods (e.g. belemnites , ammonites etc.), bony fish (e.g. lepidotes , dapedium ), sharks (e.g. Hybodus , Palaeospinax etc.) and marine Reptiles (e.g. Stenopterygius , Steneosaurus etc.).

6.4 meter long Eurhinosaurus fossil made from Holzmaden , now in the Burke Museum of Natural History and Culture in the United States

Systematics and taxonomy

Eurhinosaurus longirostris from the Urwelt-Museum Hauff

The Leptonectidae are closely related to the Temnodontidae and the Suevoleviathanidae . This monophyletic group has characteristic similarities. Its members have longipinnate fins with 3–4 primary fingers. The upper and lower jaws are greatly elongated and narrow. The eye socket is extremely large and the cheek region is reduced. The temporal windows are small, the teeth are small, pointed, narrow and have a smooth surface. The following cladogram shows the relationships within the Leptonectidae and their sister groups .

 Parvipelvia  

 Macgowania


   

 Hudsonelpidia


  Neoichthyosauria  


 Temnodontosaurus


  Leptonectidae  

 Leptonectes


   

 Excalibosaurus


   

 Eurhinosaurus





   

 Suevoleviathan


   

 Thunnosauria




Template: Klade / Maintenance / 3

Template: Klade / Maintenance / Style

Geographical distribution

Eurhinosaurus is one of the few supra-regionally distributed marine reptiles of the Toarcium. Contrary to previous opinions, Eurhinosaurus does not seem to be a rare species of its time. Maisch (1998) states that Eurhinosaurus would represent, in part, a third of all ichthyosaur finds in certain regions ( Schömberg or Dotternhausen ). The majority of the specimens come from the Posidonia schist in southwest Germany ( Holzmaden , Dotternhausen and the Lower Saxony basin in Schandelah ). Eurhinosaurus has also been found in Great Britain ( Whitby , Yorkshire), Luxembourg ( Esch-sur-Alzette ), France ( Digne-les-Bains , Alpes-de-Haute-Provence), Switzerland ( Staffelegg , Aargau) and Austria ( Salzkammergut ) .

Stratigraphy and time horizon

The stratigraphic range of Eurhinosaurus longirostris is relatively small. The species occurs for the first time in the semicelatum zone in the Lower Toarcium in Bisingen , Baden-Württemberg. The most recent fossils of this type come from the bifrons / variabilis border zone from Staffelegg in Switzerland.

Selection of museums with copies

Germany

Skull of Eurhinosaurus longirostris in the Paleontological Institute of the University of Tübingen

Austria

France

Great Britain

Switzerland

Canada

United States

Sources and References

literature

  • Christopher McGowan, Ryosuke Motani: Ichthyopterygia. In: Handbook of Paleoherpetology, Part 8, Verlag Dr. Friedrich Pfeil, 2003.

Web links

Commons : Eurhinosaurus  - collection of images, videos and audio files

Individual evidence

  1. ↑ Jäger, from GF 1856. About a new species of ichthyosaurs (Ichthyosaurus longirostris Owen et Jäger) together with remarks about the other reptiles found in the Lias formation in Württemberg. Nova acta Academiae Caesareae Leopoldino-Carolinae Germanicae naturae curiosorum 25: 937-967
  2. ↑ a b M. W. Maisch: Phylogeny, systematics, and origin of the Ichthyosauria - the state of the art. In: Palaeodiversity 3, 2010, pp. 151-214.
  3. ^ A b V. Fischer, M. Guiomar, P. Godefroit: New data on the palaeobiogeography of Early Jurassic marine reptiles: the Toarcian ichthyosaur fauna of the Vocontian Basin (SE France). In: New Yearbook for Geology and Paleontology, Abhandlungen 261, No. 1, 2011, pp. 111–127.
  4. ↑ a b c d e M. W. Maisch, AT Matzke: The Ichthyosauria. In: Stuttgart contributions to natural history series B (geology and palaeontology) 298, 2000, pp. 1–159.
  5. ↑ a b c d A. G. Reisdorf, MW Maisch, A. Wetzel: First record of the leptonectid ichthyosaur Eurhinosaurus longirostris from the Early Jurassic of Switzerland and its stratigraphic framework. In: Swiss Journal of Geosciences 104, No. 2, 2011, pp. 211-224.
  6. ↑ a b c W. Riegraf, G. Werner, F. Lörcher: The Posidonia slate: Biostratigraphy, fauna and facies of the southwest German sub-arcium (Lias ε). Ferdinand Enke Verlag, Stuttgart 1984, p. 195 ff.
  7. ↑ a b Friedrich von Huene: A new Eurhinosaurus from the upper Lias of Holzmaden. In: New Yearbook for Mineralogy, Geology and Paleontology, Department B 59, 1928, pp. 471–484.
  8. ^ Friedrich von Huene: A new find of Eurhinosaurus longirostris. In: New Yearbook for Geology and Palaeontology 93, 1951, pp. 277–284.
  9. ↑ C. McGowan, R. Motani: Ichthyopterygia. In: Handbuch der Paläoherpetologie, 8, 2003, p. 175.
  10. ^ C. McGowan: Computed tomography confirms that Eurhinosaurus (Reptilia: Ichthyosauria) does have a tailbend. In: Canadian Journal of Earth Sciences 27, No. 11, 1990, pp. 1541-1545.
  11. ^ C. McGowan: A revision of the Lower Jurassic Ichthyosaurs of Germany with descriptions of two new species. In: Palaeontographica, Department A 166, 1979, pp. 93-135.
  12. ^ J. Riess: Locomotion, swimming biophysics and phylogeny of ichthyosaurs. In: Palaeontographica, Department A 192, 1986, pp. 93-155.
  13. ↑ H.-J. Röhl, A. Schmid-Röhl: Lower Toarcian (Upper Liassic) black shales of the Central European epicontinental basin: a sequence stratigraphic case study from the SW German Posidonia Shale. In: Deposition of Organic-Carbon-Rich Sediments: Models, Mechanisms, and Consequences. Special Publication 82, 2005, pp. 165-189.
  14. ↑ MW Maisch: New specimens of the rare ichthyosaur genus Suevoleviathan MAISCH 1998 from the lower Jura of southwest Germany. In: Geologica et Paleontologica 35, 2001, pp. 145-160.
  15. ↑ MW Maisch: A new ichthyosaur genus from the Posidonia Shale (Lower Toarcian, Jurassic) of Holzmaden, SW-Germany with comments on the phylogeny of post-Triassic ichthyosaurs. In: Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 209, 1998, pp. 47–78.
  16. ^ RD Marek, BC Moon, M. Williams, MJ Benton: The skull and endocranium of a Lower Jurassic Ichthyosaur based on digital reconstructions. In: Palaeontology 58, 2015, pp. 723-742.
  17. ^ MW Maisch: Brief overview of the ichthyosaurs of the Posidonia slate with remarks on the taxonomy of the Stenopterygiidae and Temnodontosauridae. In: Jahrbuch für Geologie und Paläontologie Abhandlungen 209, No. 3, 1998, pp. 401-431.
  18. ^ C. McGowan: The taxonomic status of the Upper Liassic ichthyosaur Eurhinosaurus longirostris. In: Palaeontology 37, No. 4, 1994, pp. 747-753.
  19. ↑ E. Stüber: From the house of nature. In: Messages from the House of Nature Salzburg 14, 1998, pp. 5–10.