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Ichtyosaurs

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Leo T
826003.  Wed Jun 22, 2011 6:19 pm Reply with quote

Ichtyosaurs are (were) an order of sea-living reptiles that were contemporary with the dinosaurs. They evolved to look very much like fish, with a sleek body shape, a tail fin, a shark-like fin on their back and side fins evolved from their legs. Just like today's dolphins and whales, their ancestors lived on land.

The general shapes of ichtyosaurs, dolphins and sharks are very similar and is often used as an example of convergent evolution - similar traits that have evolved independently in different species under similar selection pressure. Other examples include the opposable thumbs of opossums and apes (including humans), the sonar sense in some bat and whale species and the antifreeze proteins in certain species of fish which evolved independently in the arctic and the antarctic.

 
Zebra57
826009.  Wed Jun 22, 2011 6:39 pm Reply with quote

welcome Leo

 
Posital
826048.  Thu Jun 23, 2011 12:35 am Reply with quote

Welcome.

Just to re-enforce: Ichtyosaurs are not dinosaurs.

 
Zebra57
826061.  Thu Jun 23, 2011 2:38 am Reply with quote

Ichthyosaur derives from the Greek for fish lizard. The top predator of the Mesozoic era evolved during the mid- Triassic era. The Cretaceous era saw the rise of the Plesiosaur (from the Greek - near(ly) lizard) which dominated the seas and saw the decline in the Ichthyosaurs.

 

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