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trogdor
Skeptic Friend
198 Posts |
 Posted - 05/15/2006 : 13:15:58
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There are other treads about fossil sharks, but I thought I would make a new one for a really cool example.
Sharks don't fossilize well. This is because they are mostly cartilage. For the most part all that is found is teeth and vertebrae. But, with these, the location of the find, the age, and a good imagination, scientists can come up with a decent idea of what the animal looked like.
But in some cases, the pieces that are found are so crazy, so ridiculously weird, that paleontologists are baffled. A great example of this is a species of shark that lived in the Permian period, called Heliocoprion. The fossil evidence looks like this:
Those are shark teeth. How they fit onto the shark is the problem.
One Russian scientist, A.P. Karpinski, tried to figure it out.
He came up with various different places the teeth could attach:
Upper jaw:
or the dorsal fin:
(These are taken from the wondrous illustrations of Ray Troll)
Most of the current information shows the teeth on the bottom jaw.
Either as a kind of circular saw:
or as a weird spiral twist:
http://dino.lm.com/images/display.php?id=86
http://dino.lm.com/images/display.php?id=87
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filthy
SFN Die Hard
USA
14408 Posts |
Posted - 05/15/2006 : 13:36:50 [Permalink]
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Damn trog, I stumbled across that fossil a couple of years ago and foolishly didn't save the article.  I've wanted to reference it since and couldn't find it, as I didn't have the name of the fish.
I think that the possibility that lower jaw was highly prehensile is a good one, as is the lower jaw & teeth being retractable into the throat, to shred it's food in passing as well as being stored there. Remarkable animal!
Good find. Thanks!
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist! 
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| Edited by - filthy on 05/15/2006 13:39:35 |
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Ricky
SFN Die Hard
USA
4907 Posts |
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filthy
SFN Die Hard
USA
14408 Posts |
Posted - 05/15/2006 : 15:57:10 [Permalink]
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Here's the article I saw on it. quote:
It is now generally agreed that the structure is indeed a complex whorl composed of up to 180 teeth and must therefore have fit somehow into the mouth. Further specimens revealed that the teeth of Helicoprion most closely resembled those of a group of Paleozoic sharks known as edestoids. One of the best-known species, Edestus giganteus, was a 20-foot (6-metre) super-predator (about the same size of the modern white shark) with teeth that kept growing beyond the tip of its snout - looking for all the world like a fish with toothy pinking shears mounted on its nose. The most likely orientation - based on the teeth of Edestus and related edestoid sharks - is that the teeth overhang from the lower jaw like the vertical blade of a circular saw, having coiled about themselves as new teeth were generated from behind. Perhaps Helicoprion used this buzz-saw arrangement to snag squid-like creatures with a sideways swipe of the head while swimming through a school of the soft-bodied molluscs. In any case, Helicoprion exemplifies some of the difficulties involved in reconstructing ancient creatures from only a few clues.
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist!
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Chippewa
SFN Regular
USA
1496 Posts |
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