Early finds
The first known illustrations of ichthyosaur bones, vertebrae, and limb elements were published by the Welshman Edward Lhuydin his Lithophylacii Brittannici Ichnographia of 1699.

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Origin
The origin of the ichthyosaurs is contentious. Until recently, clear transitional forms with

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Traditionally, animal groups are classified within a Linnaean rank-based system. Such a taxonomy was presented by Michael Werner Maisch in his 2010 review of ichthyosaur classification.
• Clade Ichthyopterygia (sensu Motani (1999))

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Size
Ichthyosaurs averaged about 2–4 m (6.6–13.1 ft) in length. Some individual specimens were as short

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Ecology
Apart from the obvious similarities to fish, ichthyosaurs also shared parallel developmental features with dolphins, lamnid sharks, and tuna. This gave them a broadly similar appearance, possibly implied similar activity

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• List of ichthyosaurs
• Timeline of ichthyosaur research
• Dolphin

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In modern phylogeny, clades are defined that contain all species forming a certain branch of the evolutionary tree. This also allows one to clearly

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