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Post by Dinotoyforum on Oct 4, 2008 23:09:58 GMT
I haven't read Sato's non-peer-reviewed abstract, I can't find it online. you'll find it in the pdf here, Page 72: "THE MAXIMUM AND MINIMUM STROKE FREQUENCIES OF FLYING BIRDS: IMPLICATION FOR THE MAXIMUM SIZE OF FLYING ANIMALS" Somehow the abstract lists the upper limit as 52kg, while the figure in the press reports is 40kg. The abstract makes no grand pronouncements (or even mention) of how these findings may relate to pterosaurs. Well Spotted Bolesey, but in the one I downloaded it is on page 67. for anyone interested : "THE MAXIMUM AND MINIMUM STROKE FREQUENCIES OF FLYING BIRDS: IMPLICATION FOR THE MAXIMUM SIZE OF FLYING ANIMALS Sato, K.1, Sakamoto, K.Q.2, Katsumata, N.1, Watanuki, Y.3, Bost, C.-A.4, and Weimerskirch, H.4 Oral Session: Monitoring Organismal Physiology, Tuesday, Sept 2nd, 1145 hrs Abstract: Birds stroke their wings in order to provide lift. The lift should be equal or larger than gravity for sustainable flight performance. However, the lift is limited by the maximum stroke frequency, which is restricted by the maximum power of their muscle. The minimum and maximum stroke frequencies of geometrically similar birds are expected to be proportional to mass-1/6 and mass-1/3, respectively. This scaling relationship imposes restrictions on the maximum size of flying animals. Comparative study was conducted using similar shaped 5 species including streaked shearwater Calanectris leucomelas (0.6 kg, n=7), white-chinned petrel Procellaria aequinoctialis (1.3 kg, n=5), sooty albatross Phoebetria fusca (2.2 kg, n=3), black-browed albatross Thalassarche melanophrys (3.5 kg, n=5) and wandering albatross Diomedea exulans (9.4 kg, n=8). Their flight performance was continuously monitored for more than two days during foraging trips using animal-borne accelerometers. Field studies were conducted during breeding periods at Crozet Islands (wandering albatross, white-chinned petres, sooty albatross in 2006/07), Kerguelen Islands (black-browed albatross in 2005/06) in South Indian Ocean, and Sangan Island, Japan (streaked shearwater in 2006). To investigate modulation of the wing stroke frequency throughout flying periods, a spectrogram of the dorso-ventral acceleration was calculated by Wavelet transformation. A newly-developed software “Ethographer” was convenient to obtain discrete stroke frequencies for each bird by unsupervised cluster analysis k-means methods. A flying bird typically stroked at a higher frequency at take-off after which stroke frequency was equilibrated within a lower narrow range throughout the subsequent cruising flight. We could obtain two discrete stroke frequencies for each individual. The lower and higher stroke frequencies were proportional to mass-0.18 and mass-0.30, respectively (R2=0.97 and 0.98). This scaling relationship agrees with the previous theoretical predictions, and implicates that the maximum size of flying animals would be 52 kg.." The abstract doesn't even mention the word pterosaur. This hubbub in the media is a non-story.
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Post by stoneage on Oct 4, 2008 23:25:25 GMT
So what does this mean for pterosaurs believed to be more them 52kg?
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Post by sbell on Oct 5, 2008 3:49:37 GMT
I'm glad I can focus everyone's energy. All I actually said was belief is not enough--prove it wrong.
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Post by sbell on Oct 5, 2008 3:50:17 GMT
Yup, that's all the 'scientist' did. But since we aren't biomechanical engineers sbell thinks we have no right to an opinion! Hmmm. This sounds like a familiar tone.
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Post by Dinotoyforum on Oct 5, 2008 9:20:31 GMT
So what does this mean for pterosaurs believed to be more them 52kg? I could mean all sorts of things. -There is error in the weight estimate for pterosaurs. It's an inexact science. -There is error in the maximum size limit estimated in this study. -'Fly' simply means active powered flight in this study? -Some pterosaurs were flightless. -The mechanics of pterosaurs was different to birds. Or something else. In any case, it's far too premature to come down on any one of these options as a conclusion based on this single unpublished study. And the scientist did publish any such conclusions.
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Post by stoneage on Oct 5, 2008 14:21:47 GMT
So what does this mean for pterosaurs believed to be more them 52kg? I could mean all sorts of things. -There is error in the weight estimate for pterosaurs. It's an inexact science. -There is error in the maximum size limit estimated in this study. -'Fly' simply means active powered flight in this study? -Some pterosaurs were flightless. -The mechanics of pterosaurs was different to birds. Or something else. In any case, it's far too premature to come down on any one of these options as a conclusion based on this single unpublished study. And the scientist did publish any such conclusions. ;D Very scientific, I think you covered all the bases. So we can't as of yet tell about Pterosaur flight. How about Argentavis its a bird? ;D
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Post by richard on Oct 5, 2008 14:26:48 GMT
well birds are birds and pterosaurs are pterosaurs, they have different anatomy so he can't say according to studies he made on birds that pterosaurs could not fly? Or did I misunderstand the info?
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Post by Dinotoyforum on Oct 5, 2008 15:16:37 GMT
"And the scientist did publish any such conclusions" I meant: "And the scientist did not publish any such conclusions." oops ;D Regarding Argentavis, most of the same criteria apply again: -There is error in the weight estimate for Argentavis. It's an inexact science. -There is error in the maximum size limit estimated in this study. -'Fly' simply means active powered flight in this study? -Argentavis was flightless. -The mechanics of Argentavis was different to the birds in the study. Or something else.
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Post by dinowight on Oct 6, 2008 20:14:47 GMT
Does this also mean any aircraft over 44 kg is also unable to fly?
I'm going to agree with Our fearless Mod, it must mean flapping flight.
There have been some suggestions that the larger Azhdarchids were more terrestrial than their smaller relatives, but there is no reason to think they didn't fly.
Plus, pterosaur wings aren't really analogous to birds wings. Feathers would react in very different ways to a large membrane.
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Post by dinowight on Oct 6, 2008 20:18:31 GMT
Yup, that's all the 'scientist' did. But since we aren't biomechanical engineers sbell thinks we have no right to an opinion! But is it an informed opinion? Just because something "makes sense" doesn't mean it's right. it would "make sense" for pterosaurs to tuck their heads back in flight, like modern long-necked birds such a pelicans and herons, yet the biomechanical evidence suggests otherwise. Everybody is entitled to an opinion, but that doesn't mean that all opinions are equally valid.
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Post by bustosdomecq on Oct 6, 2008 20:38:34 GMT
Yup, that's all the 'scientist' did. But since we aren't biomechanical engineers sbell thinks we have no right to an opinion! But is it an informed opinion? Just because something "makes sense" doesn't mean it's right. it would "make sense" for pterosaurs to tuck their heads back in flight, like modern long-necked birds such a pelicans and herons, yet the biomechanical evidence suggests otherwise. Everybody is entitled to an opinion, but that doesn't mean that all opinions are equally valid. Typical paleontological snobbery from the people who gave us archaeoraptor and t-rex proteins. Well, it was common sense that organic tissue wouldn't survive 65 million years unchanged. But it was the paleontologsits who gave their informed opinion that not only was it genuine t-rex blood vessels with proteins, but that they could even determine that it came from a pregnant female! And what was it? Bacterial sludge, as should have been expected by anyone who has handled food. Yes, not all opinions are equal. Cetibus paribus I'll take an opinion of a man on the street than a ' paleontologist's' anyday about dinosaurs.
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Post by bustosdomecq on Oct 6, 2008 20:45:51 GMT
And who prey tell is to judge what an 'informed' opinion is or not? Hmm? Only people with PhDs in the specialty? Modern science is just like the medieval papacy, except that the scholastics had finer minds
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Post by dinowight on Oct 6, 2008 20:57:30 GMT
But is it an informed opinion? Just because something "makes sense" doesn't mean it's right. it would "make sense" for pterosaurs to tuck their heads back in flight, like modern long-necked birds such a pelicans and herons, yet the biomechanical evidence suggests otherwise. Everybody is entitled to an opinion, but that doesn't mean that all opinions are equally valid. Typical paleontological snobbery from the people who gave us archaeoraptor and t-rex proteins. Well, it was common sense that organic tissue wouldn't survive 65 million years unchanged. But it was the paleontologsits who gave their informed opinion that not only was it genuine t-rex blood vessels with proteins, but that they could even determine that it came from a pregnant female! And what was it? Bacterial sludge, as should have been expected by anyone who has handled food. Yes, not all opinions are equal. Cetibus paribus I'll take an opinion of a man on the street than a ' paleontologist's' anyday about dinosaurs. Only the most deluded individual would claim that scientists never make mistakes, but to claim that because a couple of scientists were wrong means that anything any scientist says must have less weight than someone with no knowledge at all is just as bad! Anyway, is the chap who has written this paper a palaeontologist? As there seems to be no mention of anything extinct, and the experiments seem to have been performed with live birds, I would say not. The classic hypothesis that dinosaurs were wiped out by caterpillars wasn't published by a palaeontologist, it was an entomologist in a lepidopterists journal. Don't assume that anything written about dinosaurs, especially in the popular press, was written by a palaeontologist. The recent fuss about the LHC at CERN creating black holes was based entirely on the work of a german chemist ([b not ][/b]a physicist), who had used out-dated theories on blackholes to back up his hypothesis. Physicists could argue until they were blue in the face, but all you read in the papers was "World Ends Tomorrow!" and the public all going on about how those evil "Scientists" were going to kill us all! All because someone from a different discipline who was behind on the latest theories has a good PR department. But back to my point. The skull of Neovenator is not built for binocular vision. But binocular vision is useful for predators. Did Neovenator have binocular vision? Which will you believe? Conventional wisdom, or evidence?
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Post by dinowight on Oct 6, 2008 21:01:21 GMT
Incidentally, I'm not saying that large pterosaurs couldn't fly, I'm sure the original news report has either taken one of his comments out of context, or a rookie science correspondent (if they haven't replaced the post with a showbiz correspondent!) has seen this abstract, looked up flying animals that weighed more than 56kg, and made up his/her own story, not taking into account the possibility that there might be a difference between pterosaur flight and bird flight.
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Post by sbell on Oct 6, 2008 22:23:18 GMT
And who prey tell is to judge what an 'informed' opinion is or not? Hmm? Only people with PhDs in the specialty? Modern science is just like the medieval papacy, except that the scholastics had finer minds Pitldown, is that you? Either that, or we have a pretender in our midst!
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Post by dinowight on Oct 6, 2008 22:39:31 GMT
And who prey tell is to judge what an 'informed' opinion is or not? Hmm? Only people with PhDs in the specialty? Modern science is just like the medieval papacy, except that the scholastics had finer minds Sounds like Creationist talk!
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Post by richard on Oct 6, 2008 22:52:59 GMT
And who prey tell is to judge what an 'informed' opinion is or not? Hmm? Only people with PhDs in the specialty? Modern science is just like the medieval papacy, except that the scholastics had finer minds Pitldown, is that you? Either that, or we have a pretender in our midst! No, I can assure you that it's someone else... that's not piltdown's style. Well I think that what the article meant is that animals with mechanics similar to the birds' ones couldn't fly if they were very heavy. And I doubt it's referring to pterosaurs flapping since they needed it to rise, did n't they? Besides pterosaurs life would have been complicated just glading in the sky, millions of years of evolution wouldn't allow that. In addition I think that accepting every new theory just because of advances in science and technology doesn't represent something of value, see this new economic system failed afterall.
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Post by bolesey on Oct 7, 2008 0:28:29 GMT
Well Spotted Bolesey, but in the one I downloaded it is on page 67. Looks like I was going by the page numbers according to the pdf viewer(the actual numbered pages in the document are different; they don't count the introduction). So what does this mean for pterosaurs believed to be more them 52kg? It could mean all sorts of things. -There is error in the weight estimate for pterosaurs. It's an inexact science. -There is error in the maximum size limit estimated in this study. -'Fly' simply means active powered flight in this study? -Some pterosaurs were flightless. -The mechanics of pterosaurs was different to birds. Or something else. In any case, it's far too premature to come down on any one of these options as a conclusion based on this single unpublished study. And the scientist did not publish any such conclusions. As a variation on your 5th point, perhaps Pterosaurs were particularly efficient fliers compared to birds. As a 6th point, perhaps there is some environmental variable that should be taken into account. I have absolutely no idea if or how such things may have varied in the past, but changes in atmospheric density, temperature, possibly even gravity, would all presumably affect the ability of such animals to become airborne.
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Post by bjeast on Oct 7, 2008 5:09:48 GMT
Well, it is interesting to think about, but I just find it so improbable that even the big ones couldn't stay aloft. I doubt they'd take any prizes in a flying creatures acrobatics contest, but to think that these clumsy (on land) creatures survived for millions and millions of years (the various species) without being able to fly stretches credulity for me. We just haven't figured out how they pulled it off, I guess.
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Post by thagomizer on Oct 14, 2008 5:44:04 GMT
Typical paleontological snobbery from the people who gave us archaeoraptor and t-rex proteins. Do you honestly believe that all opinions are equally valid, no matter how much you know? Some people know more than other people. Not because they're better, but because they have more experience. Their opinions should be given more weight. I have no idea how anybody can possibly disagree with this. Not accepted as fact just because they know more, just given more weight. Until more info comes up or the other parties gain more experience/knowledge. Simple. Not snobbery, just simple logic. Anyway, read the DML archives. A lot of people there have more experience with pterosaur mechanics than the authors of this study, and they're universally calling BS on it.
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