Ichthyosaurus

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Ichthyosaurus
Temporal range: Late Triassic - Early Jurassic, Rhaetian–Pliensbachian
Ichthyosaurus breviceps 2.jpg
Fossil specimen of I. breviceps
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Ichthyosauria
Family: Ichthyosauridae
Genus: Ichthyosaurus
De la Beche & Conybeare, 1821
Type species
Ichthyosaurus communis
Conybeare, 1822
Species
  • I. communis Conybeare, 1822
  • I. intermedius Conybeare, 1822
  • I. breviceps Owen, 1881
  • I. conybeari Lydekker, 1888

Ichthyosaurus (derived from Greek ιχθυς/ichthys meaning 'fish' and σαυρος/sauros meaning 'lizard') is a genus of ichthyosaurs from the late Triassic and early Jurassic (Rhaetian - Pliensbachian[1]) of Europe (Belgium, England, Switzerland). It is among the best known ichthyosaur genera, with the Order Ichthyosauria being named after it.[2][3][4] Ichthyosaurus was the first complete fossil to be discovered in the early 19th century by Mary Anning in England.[5]

Description[edit]

Maximum known size of I. communis compared with a human

Ichthyosaurus were smaller than most of their relatives, with individuals measuring up to 2 metres (6.6 ft) in length. Hundreds of well-preserved, fossilised skeletons have been found in Jurassic rock at Holzmaden, Germany. Some of the bones were still articulated. Some fossils still had baby specimens inside them, indicating that Ichthyosaurus was viviparous. Similar finds in the related Stenopterygius also show this.[6][7] The German fossils also featured the outline of Ichthyosaurus's skin, revealing that it had a fleshy dorsal fin on its back and a large caudal fin. Other ichthyosaur fossils showed this feature was not limited to Ichthyosaurus.

Palaeobiology[edit]

Life restoration of I. communis
I. intermedius skull

Ichthyosaurus ear bones were solid, probably transferring water vibrations to the inner ear. Still, hunting by sight was the creature's main feeding activity; it had huge, sensitive eyes, protected by bony shields. Coprolites of Ichthyosaurus reveal that its diet consisted of fish and squid.[8]

It was initially believed that Ichthyosaurus laid eggs on land, but fossil evidence shows that in fact the females gave birth to live young. As such, they were well-adapted to life as fully pelagic organisms (i.e. they never came onto land). The babies were born tail first to prevent them from drowning in the water.[6]

The cladogram below follows the topology from a 2010 analysis by Patrick S. Druckenmiller and Erin E. Maxwell.[9]

Thunnosauria 

Ichthyosaurus




Stenopterygius




"Ophthalmosaurus" natans


 Ophthalmosauridae 


Aegirosaurus



Ophthalmosaurus (type species)





Mollesaurus




Athabascasaurus




Brachypterygius




Arthropterygius



Caypullisaurus



"Platypterygius" hercynicus



"Platypterygius" australis (=Longirostria)[10]



Platypterygius (type species)




Maiaspondylus



"Platypterygius" americanus (=Tenuirostria)[10]











Poem[edit]

Joseph Victor von Scheffels poem Der Ichthyosaurus describes its extinction in humouristic verses. A monument on Hohentwiel cites it as well.[11] The poem has been translated among others by Charles Godfrey Leland [12] Some of the stanzas:

'The rushes are strangely rustling,
The ocean uncannily gleams,
As with tears in his eyes down gushing,
An Ichthyosaurus swims.

'He bewails the frightful corruption
Of his age, for an awful tone
Has lately been noticed by many
In the Lias formation shown.
...

'The Plesiosaurus, the elder,
Goes roaring about on a spree;
The Pterodactylus even
Comes flying as drunk as can be.

'The Iguanodon, the blackguard,
Deserves to be publicly hissed,
Since he lately in open daylight
The Ichthyosaura kissed.

'The end of the world is coming,
Things can't go on long in this way;
The Lias formation can't stand it,
Is all that I've got to say!'
...

And this petrifideal ditty?
Who was it this song did write?
'Twas found as a fossil album leaf
Upon a coprolite.

References[edit]

  1. ^ Dean R. Lomax (2010). "An Ichthyosaurus (Reptilia, Ichthyosauria) with gastric contents from Charmouth, England: First report of the genus from the Pliensbachian". Paludicola 8 (1): 22–36. 
  2. ^ Maisch MW, Matzke AT. 2000. The Ichthyosauria. Stuttgarter Beiträge zur Naturkunde Serie B (Geologie und Paläontologie) 298: 1-159
  3. ^ McGowan C, Motani R. 2003. Ichthyopterygia. – In: Sues, H.-D. (ed.): Handbook of Paleoherpetology, Part 8, Verlag Dr. Friedrich Pfeil, 175 pp., 101 figs., 19 plts; München
  4. ^ Maisch MW, Reisdorf AG, Schlatter R, Wetzel A. 2008. A large skull of Ichthyosaurus (Reptilia: Ichthyosauria) from the Lower Sinemurian (Lower Jurassic) of Frick (NW Switzerland). Swiss Journal of Geosciences 101: 617-627.
  5. ^ Essesials of Anthropology 6th addition
  6. ^ a b Böttcher R. 1990. Neue Erkenntnisse über die Fortpflanzungsbiologie der Ichthyosaurier. Stuttgarter Beiträge zur Naturkunde Serie B (Geologie und Paläontologie) 164: 1-51
  7. ^ Martill D.M. 1993. Soupy Substrates: A Medium for the Exceptional Preservation of Ichthyosaurs of the Posidonia Shale (Lower Jurassic) of Germany. Kaupia - Darmstädter Beiträge zur Naturgeschichte 2: 77-97
  8. ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 80. ISBN 1-84028-152-9. 
  9. ^ Michael W. Maisch and Andreas T. Matzke (2003). "Observations on Triassic ichthyosaurs. Part XII. A new Lower Triassic ichthyosaur genus from Spitzbergen". Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 229: 317–338. 
  10. ^ a b Arkhangel’sky, M. S., 1998, On the Ichthyosaurian Genus Platypterygius: Palaeontological Journal, v. 32, n. 6, p. 611-615.
  11. ^ Werkkatalog Sieckes (PDF; 7,7 MB)
  12. ^ Charles Godfrey Leland, Gaudeamus! Humorous Poems by Joseph Viktor von Scheffel, Ebook-Nr. 35848 on gutenberg.org