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#11 | |
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Join Date: Jul 2002
Location: US east coast. And www.theroyalforums.com
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#12 | |
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Join Date: Sep 2000
Location: Alibi: ego ipse hinc extermino
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Try sharks. As already noted, eyes came before bony skulls, so skulls evolved to fit them. A key point to realise is that bone condenses out of cartilage. Sharks and rays (elasmobranchs, IIRC), unlike literally �bony fish� (teleosts), don�t have bony skulls (or bony anything else); their skeletons are made out of cartilage (hence also being called chondrichthys). Cartilage is a connective tissue, and can form rigid structures, hence it can act as a skeleton. There are even simpler fishy things in the group �agnatha� -- jawless fish such as lampreys and hagfish. Try a Google on combinations of those words with �evolution� and you should get enough info to keep you busy... Also, get Benton�s �Vertebrate Palaeontology� from the library, and check out the first couple of chapters. Cheers, Oolon |
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#13 | |
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Join Date: Jan 2002
Location: California
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E.g. Anableps: <a href="http://ebiomedia.com/gall/eyes/4eye.html" target="_blank">From the "Eye to Eye Gallery" page</a> Anableps is often refered to as "the" "four-eyed fish" but it is probably better described as a two-eyed fish specialized to look above and below the water. There is an even more spectacular example of four-eyedness in fish, mentioned by Dawkins (with a diagram) somewhere, but I can't remember the details. Separate lenses and everything though. nic [ September 09, 2002: Message edited by: Nic Tamzek ]</p> |
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