Ichthyosaurus

Ichthyosaurus Temporal range: Late Triassic - Early Jurassic, Rhaetian–Pliensbachian PreЄ Є O S D C P T J K Pg N
Fossil specimen of I.communis
Scientific classification
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 † I. ceramensis Martin, 1888 †I. anningae Lomax & Massare, 2015

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) of Europe (Belgium, England, Switzerland) and Asia (Indonesia). It is among the best known ichthyosaur genera, with the Order Ichthyosauria being named after it. Ichthyosaurus was the first complete fossil to be discovered in the early 19th century by Mary Anning in England.

Description

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. 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

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.

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.

Life restoration of I. communis

Classification

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

Thunnosauria	Ichthyosaurus Stenopterygius "Ophthalmosaurus" natans  Ophthalmosauridae  Aegirosaurus Ophthalmosaurus (type species) Mollesaurus Athabascasaurus Brachypterygius Arthropterygius Caypullisaurus "Platypterygius" hercynicus "Platypterygius" australis (=Longirostria) Platypterygius (type species) Maiaspondylus "Platypterygius" americanus (=Tenuirostria)

Poem

Joseph Victor von Scheffels poem Der Ichthyosaurus describes its extinction in humouristic verses. A monument on Hohentwiel cites it as well. The poem has been translated among others by Charles Godfrey Leland 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.

See also

• List of ichthyosaurs
• Timeline of ichthyosaur research