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Starman
SFN Regular
Sweden
1613 Posts |
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filthy
SFN Die Hard
USA
14408 Posts |
 Posted - 04/20/2005 : 04:23:01 [Permalink]
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PZ makes a good point; could be, I suppose. But I'm not comfortable with it for a couple of reasons that were mentioned in his article, notably that there is no evidence that ancient crocs were any better insulated than those of today. An uninsulated endotherm is a dead endotherm, especally an aquatic or semi-aquatic one. Also, it would have to feed constantly, and many of today's crocodilian populations, particularly some of the African nilotics, which due to their habitate, might only feed a few times a year. And crocs are not particularly deep divers, nor does any evidence beyond the heart setup demonstrate that they could have been.
Crocodilians are not particularly good swimmers, as well -- say what?! No, not when compared to endothermic animals such as pinnipeds and whales, or even otters. They are good for a quick, powerful lunge from a muddy ambush, or an extended, leasurly wallow out to sea upon occasion, but that's about it. A lot like ourselves, come to think of it...
Crocodilians have been called 'living fossils' (I hate that term!) because they show so few, basic changes from their ancient forms beyond a reduction in size.
Endothermic (maybe) dinosaurs and their pelagic kin is another matter entirely. Many if not most of these were a lot more active than crocs, and evidence is piling up that at least some of them were quite well insulated with feathers. And it is not unreasonable to speculate that some carried layers of blubber for insulation. Icthyosaurs and pliosaures(sp) for example. This would make an endothermic system into an advantage that would not much benefit a shallows-dwelling, rather seditary crocodile.
Nothing official; just my thoughts.
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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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Starman
SFN Regular
Sweden
1613 Posts |
Posted - 04/20/2005 : 05:20:47 [Permalink]
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quote:
Originally posted by filthy
PZ makes a good point; could be, I suppose. But I'm not comfortable with it for a couple of reasons that were mentioned in his article, notably that there is no evidence that ancient crocs were any better insulated than those of today. An uninsulated endotherm is a dead endotherm, especally an aquatic or semi-aquatic one. Also, it would have to feed constantly, and many of today's crocodilian populations, particularly some of the African nilotics, which due to their habitate, might only feed a few times a year.
The endothermic ancestors, if there where any, might have lived in an other environment than their exothermic decendants.
Anyway as evos cant agree on this matter Genesis must be right! |
"Any religion that makes a form of torture into an icon that they worship seems to me a pretty sick sort of religion quite honestly"
-- Terry Jones |
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filthy
SFN Die Hard
USA
14408 Posts |
Posted - 04/20/2005 : 07:21:06 [Permalink]
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quote:
Originally posted by Starman
quote:
Originally posted by filthy
PZ makes a good point; could be, I suppose. But I'm not comfortable with it for a couple of reasons that were mentioned in his article, notably that there is no evidence that ancient crocs were any better insulated than those of today. An uninsulated endotherm is a dead endotherm, especally an aquatic or semi-aquatic one. Also, it would have to feed constantly, and many of today's crocodilian populations, particularly some of the African nilotics, which due to their habitate, might only feed a few times a year.
The endothermic ancestors, if there where any, might have lived in an other environment than their exothermic decendants.
Anyway as evos cant agree on this matter Genesis must be right!
True, and doubtless they did; Crocodilia is a very old family. But how much different? How much of a change of enviornment would it take to make a radical change from ecto to endothermia evolutionarly advantageous? Especally when the modern animal is so very good at what it does and so cloesly resembles it's ancient ancestors? Tough call, eh?
But, the tough calls are the most interesting ones, and perhaps some sort of fossil evidence will turn up to answer it (can't imagine what it might be). Until then, or until some obscure translation of Genesis turns up to explain a croc's four valve heart (not holding my breath for that one, either), we'll just have to wait and wonder.
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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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