Ichthyosaurus

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Ichthyosaurus
Fossil range: Early Jurassic
A pair of Ichthyosaurus
A pair of Ichthyosaurus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Order: Ichthyosauria
Family: Ichthyosauridae
de la Beche & Conybeare, 1821
Genus: Ichthyosaurus
de la Beche & Conybeare, 1821
Species
Fossilized Ichthyosaurus skeleton.
Fossilized Ichthyosaurus skeleton.

Ichthyosaurus (derived from Greek ιχθυς meaning 'fish' and σαυρος meaning 'lizard') is an extinct genus of reptile, belonging to the aquatic ichthyosaur order, which was named after it. It is among the best known ichthyosaur genera. Ichthyosaurus was the first complete fossil to be discovered in the early 1800's by Mary Anning in England. [Essesials of Anthropology 6th addition]

Ichthyosaurus with a human to scale.
Ichthyosaurus with a human to scale.

Ichthyosaurus was smaller than most of its relatives, measuring 2 m (6 ft 8 inches) in length. Hundreds of incredibly 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 (and other ichthyosaurs) were 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.

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[citation needed].

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.