Sauropterygia
From Biocrawler, the free encyclopedia.
| Sauropterygian
Conservation status: Fossil | ||||||||
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 Artistic recreation of a plesiosaur | ||||||||
| Scientific classification | ||||||||
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| Groups | ||||||||
Sauropterygia ("lizard flippers") is a group of very successful aquatic reptiles that flourished during the Age of the Dinosaurs before they became extinct. They are united by a radical adaptation of their shoulder, designed to support powerful flipper strokes. Some later sauropterygians like the pliosaurs developed a similar mechanism in their pelvis.
The earliest sauropterygians appeared about 245 million years ago (Ma), at the start of the Triassic period. Early examples were small, semi-aquatic lizard-like animals with long limbs (pachypleurosaurs), but they quickly grew to be several meters long and spread into shallow waters (nothosaurs). The Triassic-Jurassic extinction event wiped them all out except for the plesiosaurs, who diversified quickly in the early Jurassic into long- and short-necked, fully aquatic forms. Disregarding reports of lake monsters like the Loch Ness Monster, they all perished 65 Ma during the Cretaceous-Tertiary extinction event.
Classification is difficult because the demands of the aquatic environment caused the same characteristics to evolve multiple times, in an example of convergent evolution. While sauropterygians are considered diapsids, they are also sometimes classified with turtles. The bulky-bodied placodonts may also be sauropterygians. In addition to the modifications of the shoulder, the group is also united by several modifications in their skulls.
External links
- Unit 220: 100: Lepidosauromorpha (http://www.palaeos.com/Vertebrates/Units/220Lepidosauromorpha/220.100.html). Palaeos. July 15, 2003. Retrieved January 19, 2004.
- Sauropterygia: Flipper reptiles — longnecks and bigheads (http://dinosauricon.com/taxa/sauropterygia.html). T. Mike Keesey. The Dinosauricon. Retrieved January 19, 2004.
- A review of the Sauropterygia (http://www.geocities.com/sea_saur/classification.html). Adam Stuart Smith. The Plesiosaur Directory. Retrieved January 19, 2004.
