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Author | Topic: Creationist response to cetacean femur, leg atavism, and limb bud. | ||||||||||||||||||||||||||||||||||||||||||||
Trae Member (Idle past 4306 days) Posts: 442 From: Fremont, CA, USA Joined:
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Aaron writes:
A favorite quote by what possible standard? Neither Google nor Bing shows it used often and most the listings are duplicates, closely linked to the same poster, or posted by creationists. In addition, you’ve not posted the entirety of the quote.
He begins his 1881 paper by saying Nothing can be imagined more useless to the animal than rudiments of hind legs entirely buried beneath the skin of a whale. Of course, this is a favorite quote of evolutionists. What use would legs be if hidden inside the body? http://books.google.com/books?id=HE8CAAAAYAAJ&pg=PA228&lp... Nothing can be imagined more useless to the animal than rudiments of hind-legs entirely buried beneath the skin of a whale, so that one is inclined to suspect that these structures must admit of some other interpretation.
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Aaron Member (Idle past 3959 days) Posts: 65 From: Kent, WA Joined: |
Granny M,
Can you suggest why a bone tumour should overwhelmingly favour that site? Further, since you are explicit about your belief that God created the whale, why would he create them so as to display bone tumours that so closely resemble femurs that even the world's top zoologists can be fooled? Maybe I wasn't clear enough. I don't think the femur bones are bone tumors. My only mention of anything being a tumor was the one specific fin whale pelvis with the small nodule fused to the edge of the pelvis. I said in that case that it was difficult to tell if the nub was a tumor or the femur fused to the pelvis - and either way, that was an abnormal case, since a normal cetacean pelvis doesn't have anything fused to it.
Just because two mammals have a muscle, that extends from the pelvis to the base of the penis/clitoris, doesn't mean that there is any connection between those muscles. Uh-huh. But the paper I just cited disagrees with Brazier. Clearly it is more debatable than you think.
Calculating homology between muscles involves more than identifying common connection points - I'm sure its more complicated than either of us could really debate at length. Either way, the paper you cited doesn't dispute Brazier's point about nerve differences in the muscles between cetaceans and other mammals. The author disputes Arvy's contention that there is no homology - not Brazier's point that homology is extremely difficult to decipher. The author also cites a paper by Bejder and Hall which cites Brazier's comments - but does not disagree with him.
You are cherry-picking. If you think that Tajima possesses sufficient expertise to correctly diagnose an active role in locomotion of the cetacean pelvis, then you really ought to credit him with enough expertise to tell which muscle is which.
I don't disagree with Tajima. He says the aponeurotic sheet has a similar connection point. That's the straight up data. How he interprets that data evolutionarily is another matter. I'm sure there are similar muscles in similar positions that play similar roles. When you read Struthers, you see how some muscles have similarities, but others he has a hard time labeling because of how drastically different they are in their connection points from a terrestrial animal. Either way, it is not a major building block of my arguments. Edited by Aaron, : No reason given.
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Aaron Member (Idle past 3959 days) Posts: 65 From: Kent, WA Joined: |
Dr. A
Dorudon has three foot digits (which is less than his forelimb). I could only see two on the photograph; do you have a reference? Thanks. I just recently photographed the hind limbs of a Dorudon and Basilosaurus skeleton. The Dorudon limb is very much like this diagram of Basilosaurus - although it is hard to tell from this diagram how the femur articulates with the pelvis. It doesn't lay flat to it, but is extended perpendicular to it.
Well according to this, that isn't a "rounded carpal bone", or even a rounded tarsal bone. That's the femur (or, according to your "front limb" hypothesis, the humerus). The next two bones are the tibia and fibula (or, according to your "front limb" hypothesis, the radius and ulna); there are no tarsals (or carpals); and then after that we get into phalanges. I guessed at calling it a carpal bone - based on the typical bones in a hand. Whatever it is, the rounded shape is the same as the bone in a sperm whale front flipper.
Seriously, again I'd like a look at your source material before coming to a conclusion.
The 4 foot + limb atavism in the humpback can be found here:Hind Limb Rudiments on Modern Whales Example Two Now, you did not mean that you had probably read reports saying this about Dorudon, did you? You meant that this was probably true of Dorudon, did you not? So how did I misrepresent you? What I meant is that I didn't pull the idea of sexual claspers out of my rear (not sure if you were insinuating that). The idea was first put forth by someone else. In that sense, the claim isn't mine - though I agree with him.
This paper, for example, on the humpbacked whale, describes an embryonic stage at which the "peg-like hind limb buds" are visible and "a bilateral thickening, the milk line, extends between the limbs". The ridge and the hind limb buds are two different things. Like in all the other mammals. Thanks for the link - that's a paper I hadn't read yet. The ridge extends between the forelimb and the hindbud, not between the two hindbuds (not sure if you thought this, but the wording is a little tricky.) And the milk line connects to the nipple. I didn't mean to imply that what we see in humans is an exact one to one comparison of the cetacean condition - just that the forming of the mammary glands involve the appearing, disappearing, and reappearing of certain structures. In cetaceans, the developmental process is more complex, involving the forming of mammary clefts - in which the nipple reside. The Ryder study I first cited wasn't linking the buds to the milk lines - but to other parts of the organ such as the rudimentary mammary clefts. BTW, I've run my main points by several marine biologists and none argued against them. I received some helpful comments and advice - and plenty of affirmation, including on this point of the mammary glands. Edited by Aaron, : No reason given.
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Dr Adequate Member (Idle past 284 days) Posts: 16113 Joined: |
Epipubic bones are bones very similar to the femur remnant found in cetaceans ... "Very" similar? I would dispute this.
Interestingly, they were not considered limb buds back in the 1880s. At that time, the tail was considered to be the evolutionary equivalent of the hind limbs fused together. Do you have a primary source for this, please? Only it seems incredible to me that any anatomist could look at the caudal vertebrae of a whale and not identify them as caudal vertebrae. Edited by Dr Adequate, : No reason given.
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Granny Magda Member Posts: 2462 From: UK Joined: Member Rating: 4.0
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Hi Aaron,
Maybe I wasn't clear enough. I don't think the femur bones are bone tumors. My only mention of anything being a tumor was the one specific fin whale pelvis with the small nodule fused to the edge of the pelvis. I understand that. You still have no evidence that this is a tumour though. I agree that it is an abnormal case.
Calculating homology between muscles involves more than identifying common connection points - I'm sure its more complicated than either of us could really debate at length. Either way, the paper you cited doesn't dispute Brazier's point about nerve differences in the muscles between cetaceans and other mammals. The author disputes Arvy's contention that there is no homology - not Brazier's point that homology is extremely difficult to decipher. Nonetheless, that paper does identify homologies, so it can't be that much of a problem. Your only answer to this is that they are engaged in wishful thinking, which I find rather dismissive.
The author also cites a paper by Bejder and Hall which cites Brazier's comments - but does not disagree with them. I think that is too tenuous to be regarded as direct support for Brazier's statement. The fact remains that work is being done to identify homologies in the muscles around the whale's hind limb. The work is being done and, difficult though it may be, those homologies are being found. Clearly Brazier was over-egging it a little when he said it was "utterly impossible".
I don't disagree with Tajima. He says the aponeurotic sheet has a similar connection point. That's the straight up data. How he interprets that data evolutionarily is another matter. So you do disagree with Tajima. You selectively disagree with him, based not upon his paper or its contents, but upon your preconceived bias against evolutionary explanations. The fact remains that the paper you cited explicitly describes the ischiocavernosus as being homologous with that of terrestrial mammals.
When you read Struthers, you see how some muscles have similarities, but others he has a hard time labeling because of how drastically different they are in their connection points from a terrestrial animal. Either way, it is not a major building block of my arguments. Is there a major building block of your argument that you feel I have not addressed? Oh, by the way, you may have noticed that I mentioned sirenians up thread. Sirenians are the group that includes manatees and dugong. They are aquatic mammals too. Guess what they have...
Given that your explanations for the cetacean pelvis have so far been somewhat piecemeal, I can't help but wonder how you explain the presence of hind-limb remnants in yet another aquatic mammal. Mutate and Survive On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage
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Granny Magda Member Posts: 2462 From: UK Joined: Member Rating: 4.0 |
BTW, I've run my main points by several marine biologists and none argued against them. I received some helpful comments and advice - and plenty of affirmation, including on this point of the mammary glands. Your main points are;a) Evolution is false; b) Living things were created by God and; c) Whales did not evolve from terrestrial vertebrates. Did you run any of that past those biologists? Mutate and Survive On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage
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Aaron Member (Idle past 3959 days) Posts: 65 From: Kent, WA Joined: |
Do you have a primary source for this, please? Only it seems incredible to me that any anatomist could look at the caudal vertebrae of a whale and not identify them as caudal vertebrae. I may not have all the details correct of how they thought the limbs turned into the tail - but this book by Ryder talks about how the tail fluke is related to the feet: On the Development of the Cetacea: Together with a Consideration of the ... - John Adam Ryder - Google Books In describing an embryo he says: "provided the fluke folds be regarded as representative of the hinder limb folds..."
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Dr Adequate Member (Idle past 284 days) Posts: 16113 Joined: |
I just recently photographed the hind limbs of a Dorudon and Basilosaurus skeleton. Cool, can we see? Does the hind limb of Dorudon have three digits? Only as I say I can only see two on the photograph I linked to.
I guessed at calling it a carpal bone - based on the typical bones in a hand. I'd have guessed the same, but I am supposing that the people who actually looked at the whale must have had some reason for dismissing the intepretation that seemed obvious to us. People like things that seem obvious.
Whatever it is, the rounded shape is the same as the bone in a sperm whale front flipper. ... or in the hind limbs of other mammals. Also I would point out that we don't really know its shape, we know its silhouette as x-rayed from one angle. My femur would look that shape if you x-rayed it end on ...
The 4 foot + limb atavism in the humpback can be found here: Hind Limb Rudiments on Modern Whales Example Two Thanks.
What I meant is that I didn't pull the idea of sexual claspers out of my rear (not sure if you were insinuating that). I wasn't. What is troublesome about your agreement that they are sexual claspers is that you also seem to believe that they were specially designed by God for that purpose ... in which case it is odd how strikingly they resemble legs specially designed for walking with.
BTW, I've run my main points by several marine biologists and none argued against them. And yet there do seem to be one or two howlers in there ...
I received some helpful comments and advice - and plenty of affirmation, including on this point of the mammary glands. Lets be clear about this. Does anyone affirm that the hind limb buds are incipient mammary glands?
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Dr Adequate Member (Idle past 284 days) Posts: 16113 Joined: |
I may not have all the details correct of how they thought the limbs turned into the tail - but this book by Ryder talks about how the tail fluke is related to the feet: Yes, he thought that the flukes were the feet, but not that the tail was the legs. As to your original assertion:
At that time, the tail was considered to be the evolutionary equivalent of the hind limbs fused together. ... Ryder himself didn't believe this, and he makes it clear that even his views on flukes were heterodox in his day:
... such a view [i.e. Ryder's] may, I venture to think, impress the fairminded student as being a little nearer the truth than the comparatively modern assumption universally sustained up to the present year by the most eminent of living morphologists, amongst whom must be named Huxley, Flower, Claus, Owen, and Parker, that the hind limbs of Cetacea have been totally suppressed or atrophied outwardly, thus leading to the avowed or tacitly admitted conclusion that the flukes, like the dorsal fin, are appendages which have been secondarily acquired or added to the morphological combination presented by the Cetacean organization ...
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Aaron Member (Idle past 3959 days) Posts: 65 From: Kent, WA Joined: |
Cool, can we see?
Here's Dorudon. I wasn't focused on number of digits, so this isn't the best angle. I have a better shot of the digits but it is a bit blurry.
Here's Basilosaurus:
Lets be clear about this. Does anyone affirm that the hind limb buds are incipient mammary glands? Yes. I had a nice back and forth with a scientist who examined the buds and wrote a widely cited paper on it. He now sees it my way.
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Aaron Member (Idle past 3959 days) Posts: 65 From: Kent, WA Joined: |
Granny,
Is there a major building block of your argument that you feel I have not addressed? I think you have done a good job raising questions and concerns. I've been a little vague with references and such because I'm not looking to "show my whole hand" so to speak. This isn't the primary outlet I'm looking to disseminate my theories through. Once I'm finished with the final paper and it has been published, I'll send you a copy to check out all the references and the additional details of my arguments. Speaking with you both has been helpful in seeing what details I need to refine.
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Taq Member Posts: 9973 Joined: Member Rating: 5.7 |
Oh, by the way, you may have noticed that I mentioned sirenians up thread. Sirenians are the group that includes manatees and dugong. They are aquatic mammals too. Guess what they have...
Another interesting tidbit is toenails on the forefins: Wikimedia Error Or perhaps they are just evenly spaced tumors. Who knows . . .
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Dr Adequate Member (Idle past 284 days) Posts: 16113 Joined: |
Once I'm finished with the final paper and it has been published, I'll send you a copy to check out all the references and the additional details of my arguments. Wouldn't it be better if it was checked before publication? You've made some pretty bad blunders so far, and it would take a lot of luck for the stuff you haven't had scrutinized to be completely accurate. Edited by Dr Adequate, : No reason given.
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Dr Adequate Member (Idle past 284 days) Posts: 16113 Joined: |
Here's Dorudon. I wasn't focused on number of digits, so this isn't the best angle. I have a better shot of the digits but it is a bit blurry. Thanks It does have a third digit. It is still more like the atavistic hindlimb than is the forelimb of a modern whale.
Yes. I had a nice back and forth with a scientist who examined the buds and wrote a widely cited paper on it. He now sees it my way. Who is he, and more importantly what exactly did he say? Your interpretations of the writings of scientists are somewhat ... haphazard, shall we say?
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Robert Byers Member (Idle past 4368 days) Posts: 640 From: Toronto,canada Joined: |
Granny Magda writes: HI Robert, Oh dear. You have decided to clutter up Aaron's nice thread. Suffice to say that, where Aaron brings evidence, you bring nothing. You say "This YEC creationist insists", as though your insistence alone could make your fantasies true. It's pathetic. Even worse, where you do make specific claims, you are painfully wrong.
Robert Byers writes: In fact only these creatures obviously first land creatures have these vestiges. That is wrong. Not just a little bit wrong, but staggeringly, woefully, embarrassingly wrong. Just google Sirenians to see how wrong you are. They display very similar hind-limb structures to those of whales. Further, there are vestiges and homologies throughout the animal kingdom. That is evolution you strange man. Look, you're not achieving anything here beyond letting your amazing ignorance hang out for all to see, so might I ask that you don't mess up this nice thread with your vague and semi-literate ramblings? Please? Thank You. Mutate and Survive I said and meant marine mammals. Not just whales.Your wrong about vestigial remnants being common in the animal etc kingdom. In fact I would guess 98% do not have any anatomical remains of previous states of evolutionary stages. The few make the case against evolution. Anyways I welcome all evidence to prove that marine mammals did first come from the land.I think this will be a future creationist correction and new opinion. They too quickly ignored this special case.
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