swansont Posted May 20, 2011 Posted May 20, 2011 Swansont, I have not "moved the goalposts", you have picked a time period not relevant to the subject at hand, which is the GTME theory. Sure you did. I made a claim, that we know that the earth's rotation rate has changed, and you redefined the conditions. Since we know that the earth's rotation has changed over time, there's no reason to think that it did not do so at some specific time in the past, i.e we assume that the laws of physics still worked. Since it's your contention that the interior reshuffled itself, it's up to you to provide evidence. It's your burden of proof. This theory posits that as Pangea formed, the core elements moved away from their current geocentric position and that total angular momentum DID NOT CHANGE because one of two things occurred to prevent that change: Either: 1. The Earth’s angular velocity changed (i.e., increased, meaning a shorter day) or 2. The Earth’s core elements moved off-center. Therefore, it is you who have "moved the goalposts." You wrote: "How much reshuffling of mass do you contend will happen by moving the continents around? How big of an effect on gravity will there be as a result? " I can’t give you an accurate answer because it depends on the displacement of the core elements. Also, the lowering of "g" near Pangea increased the height of sea levels near Pangea, effectively increasing the mass (in addtion to continental mass) that came into play. The surface gravity would have varied around the planet because the distance from the new center of mass to points on the surface would be different. Lowest "g" on Pangea would be in the region near the equator and highest "g" at high north and south latitudes. One could guess at "g" based on the size of the largest dinosaurs or largest pterosaurs....but this would only be a guess. But you should be able to estimate this. You take the mass of the continents, and change their location, which changes the moment of inertia of the planet. You can then calculate how much mass you'd need to move around to compensate. Then see what effect it has on gravity.
Earthling Posted May 20, 2011 Author Posted May 20, 2011 moontanman, You have provided Wiki links related to gravity but you have still not explained how any laws of physics have been broken. You wrote: "You also falsely suggest that the mass of the crust can significantly change the gravity if it shifts....." You have to study the concepts of moment of inertia and angular momentum (including conservation of) to understand how continental movement could cause the internal redistribution of mass within the Earth. michel123456, I was able to download the the file using the new link. The basic point is that: 1. During the last 12,000 years the GAD model is accurate within 3 degrees (95%). 2. During Cenozoic and late Mesozoic (about 65mya) the accuracy of GAD drops to 5 degrees. 3. Before the above period the paper doesn’t give GAD accuracy figures. In general, this supports the GTME because after Pangea started breaking apart the core elements would have been returning to their current geocentric position. And therefore, while returning to the current GAD status, one would expect to see decreasing (degrees) accuracy numbers, which is what this paper shows. It’s when you go back to the period when Pangea was fully consolidated (and the core elements were displaced the most) that they have problems, proven by the Pangea A, A1, B and a few other configurations. These multiple configuration problems disappear when the shifting core element theory is examined. Swonsont, You wrote: "Sure you did. I made a claim, that we know that the earth's rotation rate has changed, and you redefined the conditions. Since we know that the earth's rotation has changed over time, there's no reason to think that it did not do so at some specific time in the past, i.e we assume that the laws of physics still worked. Since it's your contention that the interior reshuffled itself, it's up to you to provide evidence. It's your burden of proof." You provided a link to a summary of a paper that suggests that the Earth’s angular velocity was higher over 600 mya. While I have no way of verifying this, I’ll assume it is correct. I also have no way of knowing if this change in AV was the result of bolide impact, whether it occurred over a long or short period, whether AV was that value for hundreds of millions of years before then, etc. because you have not done any research.... you have just searched for site that seems to indicate a change in the Earth’s AV in the past. Again, it is not relevant because it is over 300 million years before Pangea consolidated and you have no explanation why the change took place. Your statement: "Since we know that the earth's rotation has changed over time, there's no reason to think that it did not do so at some specific time in the past..." Your logic is faulty here unless you know why AV changed in the past. You wrote: "But you should be able to estimate this. You take the mass of the continents, and change their location, which changes the moment of inertia of the planet. You can then calculate how much mass you'd need to move around to compensate. Then see what effect it has on gravity." It’s not a simple calculation.....we’re not using point masses. Estimating the mass of each continent, without knowing the topography at that time or even the surface area would give questionable results. As I stated in an earlier post, as Pangea consolidated, surface gravity decreased causing very high sea levels. One would have to include the mass of the additional sea levels, and that would be latitude-dependent (i.e. a gradient...higher sea levels near the equator). Finally, we can’t assume that the core elements maintained their current spherical symmetry as they moved off-center.
swansont Posted May 21, 2011 Posted May 21, 2011 Swonsont, You wrote: "Sure you did. I made a claim, that we know that the earth's rotation rate has changed, and you redefined the conditions. Since we know that the earth's rotation has changed over time, there's no reason to think that it did not do so at some specific time in the past, i.e we assume that the laws of physics still worked. Since it's your contention that the interior reshuffled itself, it's up to you to provide evidence. It's your burden of proof." You provided a link to a summary of a paper that suggests that the Earth’s angular velocity was higher over 600 mya. While I have no way of verifying this, I’ll assume it is correct. I also have no way of knowing if this change in AV was the result of bolide impact, whether it occurred over a long or short period, whether AV was that value for hundreds of millions of years before then, etc. because you have not done any research.... you have just searched for site that seems to indicate a change in the Earth’s AV in the past. Again, it is not relevant because it is over 300 million years before Pangea consolidated and you have no explanation why the change took place. Your statement: "Since we know that the earth's rotation has changed over time, there's no reason to think that it did not do so at some specific time in the past..." Your logic is faulty here unless you know why AV changed in the past. It's fairly well established that the speed has changed. As I said, the burden of proof here is yours. You wrote: "But you should be able to estimate this. You take the mass of the continents, and change their location, which changes the moment of inertia of the planet. You can then calculate how much mass you'd need to move around to compensate. Then see what effect it has on gravity." It’s not a simple calculation.....we’re not using point masses. Estimating the mass of each continent, without knowing the topography at that time or even the surface area would give questionable results. As I stated in an earlier post, as Pangea consolidated, surface gravity decreased causing very high sea levels. One would have to include the mass of the additional sea levels, and that would be latitude-dependent (i.e. a gradient...higher sea levels near the equator). Finally, we can’t assume that the core elements maintained their current spherical symmetry as they moved off-center. You chose to post in the physics section. How about doing some damn physics instead of just waving your hands?
Moontanman Posted May 21, 2011 Posted May 21, 2011 (edited) You have to study the concepts of moment of inertia and angular momentum (including conservation of) to understand how continental movement could cause the internal redistribution of mass within the Earth. Earthling, I have request, please use the quote system, I misread your last post and thought you were claiming I was saying something I was not. I have already been embarrassed once in this thread due to a misunderstanding so lets make sure I at least know what you are really asserting. Here is what I get from what you are saying. #1. The Earths gravity must have been lower during the time of the dinosaurs, more or less 200,000,000 years ago to 65 million years ago because you claim the dinosaurs were too large to have existed if the gravity was the same or similar to what we experience now. #2. This lower gravity was caused by a shift in less than 0.374% of the Earth's mass. #3. This shift caused the molten mantle and core of the Earth to be offset so much the earths gravity was changed to 40% of what it is now during the 200,000,000 years ago to 65,000,000 years ago which is the time the dinosaurs evolved and diversified. #4. This offset of the Earths mass lasted more or less 150,000,000 years. #5. This reduction in the Earths gravity was limited to more or less the continent of Pangaea. Am I on track so far? Edited May 21, 2011 by Moontanman
Earthling Posted May 22, 2011 Author Posted May 22, 2011 swansont, You wrote: "It's fairly well established that the speed has changed. As I said, the burden of proof here is yours." I’m not going to go around in circles on this. If you are not willing to admit that the Earth’s angular velocity did not change significantly during the formation of Pangea, which is the only time relevant in this thread, then I won’t waste any time responding to your comments. Moontanman, My comments follow your statements: #1. The Earths gravity must have been lower during the time of the dinosaurs, more or less 200,000,000 years ago to 65 million years ago because you claim the dinosaurs were too large to have existed if the gravity was the same or similar to what we experience now. Yes, although the time period is probably closer to 250,000,000 to 65mya and surface gravity didn't abruptly change to today's level 65mya. The rate of increase was high at that time but continued to gradually increaseafter that. #2. This lower gravity was caused by a shift in less than 0.374% of the Earth's mass. No, the movement of the continental plates latitudinally (because only that would alter angular momentum) caused the core elements to shift to conserve angular momentum. The continental plate mass, if I would estimate, would be about 1%. In addition, as I posted earlier, as surface gravity lowered near Pangea (and correspondingly increased antipodally to Pangea), sea levels rose substantially near Pangea (and lowered antipodally). The additional mass of the higher sea levels must be added to the ~1% of continental mass. I do not know what % would have to be added to account for this. The core elements (inner/outer cores and densest part of lower mantle) I estimate to be ~85% of the mass of the Earth. Therefore, movement of 1% + x% of the plates/water resulted in a shift of the core elements in order to maintain constant angular momentum. #3. This shift caused the molten mantle and core of the Earth to be offset so much the earths gravity was changed to 40% of what it is now during the 200,000,000 years ago to 65,000,000 years ago which is the time the dinosaurs evolved and diversified. Basically yes, whether it was 40% I don’t know but I would guess 40-50%. #4. This offset of the Earths mass lasted more or less 150,000,000 years. It would have lasted much longer, and of course, the amount of offset would depend on the continental positions. 65mya, the plates were moving toward today’s position so that surface gravity gradually increased during that period. #5. This reduction in the Earths gravity was limited to more or less the continent of Pangaea. No, the effects were global and there was a gravitational gradient around the Earth. To see this, use a compass to draw a circle. Then move the point of the compass horizontally about half of the radius and widen the compass arc so that it is tangent with the furthest arc of the original circle and draw a second circle. The gap between the two circles is an indication of relative surface gravity....the wider the gap the higher the surface gravity. Therefore, lowest surface gravity was on Pangea (lowest near equator, higher near poles) and highest antipodally to Pangea, which was ocean. Am I on track so far? Yes.
mooeypoo Posted May 22, 2011 Posted May 22, 2011 swansont, You wrote: "It's fairly well established that the speed has changed. As I said, the burden of proof here is yours." I'm not going to go around in circles on this. If you are not willing to admit that the Earth's angular velocity did not change significantly during the formation of Pangea, which is the only time relevant in this thread, then I won't waste any time responding to your comments. You're the one going in circles, Earthling. I don't see what the problem is to provide proof; surely, you have some, judging by the claims you're making. You keep refusing to bring evidence, and then act surprise when we have a problem with your statements. The burden of proof is yours because you're making the claim that is not proven. I think you should go over our rules of what you're supposed to do to support your own theory, and start cooperating back with us. ~mooey
Moontanman Posted May 22, 2011 Posted May 22, 2011 Moontanman, My comments follow your statements: Ok, I'll use the quote system for you. Moontanman said #1. The Earths gravity must have been lower during the time of the dinosaurs, more or less 200,000,000 years ago to 65 million years ago because you claim the dinosaurs were too large to have existed if the gravity was the same or similar to what we experience now. earthlings answer Yes, although the time period is probably closer to 250,000,000 to 65mya and surface gravity didn't abruptly change to today's level 65mya. The rate of increase was high at that time but continued to gradually increaseafter that. Dinosaurs and mammals both evolved at about the same time, dinosaurs were superior to mammals for at least two reasons, they had better respiratory systems and stronger bones, both of which allowed them to exploit larger body size better than other animals, no need for lower gravity. There is no evidence that animals the size of dinosaurs are impossible or even improbable at the surface gravity of today. If you think creatures the size of dinosaurs were impossible i suggest you give some evidence of this, current knowledge disagrees with you. moontanman said #2. This lower gravity was caused by a shift in less than 0.374% of the Earth's mass. earthling said: No, the movement of the continental plates latitudinally (because only that would alter angular momentum) caused the core elements to shift to conserve angular momentum. The continental plate mass, if I would estimate, would be about 1%. In addition, as I posted earlier, as surface gravity lowered near Pangea (and correspondingly increased antipodally to Pangea), sea levels rose substantially near Pangea (and lowered antipodally). The additional mass of the higher sea levels must be added to the ~1% of continental mass. I do not know what % would have to be added to account for this.The core elements (inner/outer cores and densest part of lower mantle) I estimate to be ~85% of the mass of the Earth. Therefore, movement of 1% + x% of the plates/water resulted in a shift of the core elements in order to maintain constant angular momentum. I suggest you reread this link http://en.wikipedia.org/wiki/Gauss%27s_law_for_gravity and this one http://en.wikipedia.org/wiki/Gauss%27s_law_for_gravity and read this one as well http://www.solarviews.com/eng/earthint.htm Continental crust: 0.374% of Earth's mass Moontanman said #3. This shift caused the molten mantle and core of the Earth to be offset so much the earths gravity was changed to 40% of what it is now during the 200,000,000 years ago to 65,000,000 years ago which is the time the dinosaurs evolved and diversified. Basically yes, whether it was 40% I don’t know but I would guess 40-50%. Again. do you have any evidence for this? Your guess is not good enough and is based on false data as is pointed out in the link i provided. Moontanman said #4. This offset of the Earths mass lasted more or less 150,000,000 years. It would have lasted much longer, and of course, the amount of offset would depend on the continental positions. 65mya, the plates were moving toward today’s position so that surface gravity gradually increased during that period. So far you have not given any evidence that this shift of 0.375% of the earths mass occurred or could have occurred much less that it would have changed the earths gravity. moontanman said #5. This reduction in the Earths gravity was limited to more or less the continent of Pangaea. No, the effects were global and there was a gravitational gradient around the Earth. To see this, use a compass to draw a circle. Then move the point of the compass horizontally about half of the radius and widen the compass arc so that it is tangent with the furthest arc of the original circle and draw a second circle. The gap between the two circles is an indication of relative surface gravity....the wider the gap the higher the surface gravity. Therefore, lowest surface gravity was on Pangea (lowest near equator, higher near poles) and highest antipodally to Pangea, which was ocean. Again you have shown no eviedence of this happening other than the size of the dinosuars which is false. moontanman asked: Am I on track so far? Yes. then i have falsified your claims unless you have some evidence of your claims other than your guesses.
Moontanman Posted May 22, 2011 Posted May 22, 2011 (edited) Moontanman, My comments follow your statements: Ok, I'll use the quote system for you. Moontanman said #1. The Earths gravity must have been lower during the time of the dinosaurs, more or less 200,000,000 years ago to 65 million years ago because you claim the dinosaurs were too large to have existed if the gravity was the same or similar to what we experience now. earthlings answer Yes, although the time period is probably closer to 250,000,000 to 65mya and surface gravity didn't abruptly change to today's level 65mya. The rate of increase was high at that time but continued to gradually increaseafter that. Dinosaurs and mammals both evolved at about the same time, dinosaurs were superior to mammals for at least two reasons, they had better respiratory systems and stronger bones, both of which allowed them to exploit larger body size better than other animals, no need for lower gravity. There is no evidence that animals the size of dinosaurs are impossible or even improbable at the surface gravity of today. If you think creatures the size of dinosaurs were impossible i suggest you give some evidence of this, current knowledge disagrees with you. moontanman said #2. This lower gravity was caused by a shift in less than 0.374% of the Earth's mass. earthling said: No, the movement of the continental plates latitudinally (because only that would alter angular momentum) caused the core elements to shift to conserve angular momentum. The continental plate mass, if I would estimate, would be about 1%. In addition, as I posted earlier, as surface gravity lowered near Pangea (and correspondingly increased antipodally to Pangea), sea levels rose substantially near Pangea (and lowered antipodally). The additional mass of the higher sea levels must be added to the ~1% of continental mass. I do not know what % would have to be added to account for this.The core elements (inner/outer cores and densest part of lower mantle) I estimate to be ~85% of the mass of the Earth. Therefore, movement of 1% + x% of the plates/water resulted in a shift of the core elements in order to maintain constant angular momentum. I suggest you reread this link http://en.wikipedia.org/wiki/Gauss%27s_law_for_gravity and this one http://en.wikipedia.org/wiki/Shell_theorem and read this one as well http://www.solarviews.com/eng/earthint.htm Continental crust: 0.374% of Earth's mass Moontanman said #3. This shift caused the molten mantle and core of the Earth to be offset so much the earths gravity was changed to 40% of what it is now during the 200,000,000 years ago to 65,000,000 years ago which is the time the dinosaurs evolved and diversified. Basically yes, whether it was 40% I don’t know but I would guess 40-50%. Again. do you have any evidence for this? Your guess is not good enough and is based on false data as is pointed out in the link i provided. Moontanman said #4. This offset of the Earths mass lasted more or less 150,000,000 years. It would have lasted much longer, and of course, the amount of offset would depend on the continental positions. 65mya, the plates were moving toward today’s position so that surface gravity gradually increased during that period. So far you have not given any evidence that this shift of 0.375% of the earths mass occurred or could have occurred much less that it would have changed the earths gravity. moontanman said #5. This reduction in the Earths gravity was limited to more or less the continent of Pangaea. No, the effects were global and there was a gravitational gradient around the Earth. To see this, use a compass to draw a circle. Then move the point of the compass horizontally about half of the radius and widen the compass arc so that it is tangent with the furthest arc of the original circle and draw a second circle. The gap between the two circles is an indication of relative surface gravity....the wider the gap the higher the surface gravity. Therefore, lowest surface gravity was on Pangea (lowest near equator, higher near poles) and highest antipodally to Pangea, which was ocean. Again you have shown no eviedence of this happening other than the size of the dinosuars which is false. moontanman asked: Am I on track so far? Yes. then i have falsified your claims unless you have some evidence of your claims other than your guesses. Edited May 22, 2011 by Moontanman
Earthling Posted May 23, 2011 Author Posted May 23, 2011 Moontanman, You wrote: "Dinosaurs and mammals both evolved at about the same time, dinosaurs were superior to mammals for at least two reasons, they had better respiratory systems and stronger bones, both of which allowed them to exploit larger body size better than other animals, no need for lower gravity. There is no evidence that animals the size of dinosaurs are impossible or even improbable at the surface gravity of today. If you think creatures the size of dinosaurs were impossible i suggest you give some evidence of this, current knowledge disagrees with you." Dinosaurs and mammals did not evolve at the same time. If you think dinosaurs that come close to the size of whales could live on land today, you are entitled to your opinion.....I will not ask you to prove that. You wrote: "I suggest you reread this link http://en.wikipedia...law_for_gravty and this one http://en.wikipedia....i/Shell_theorem and read this one as well http://www.solarview...ng/earthint.htm What' s your point concerning the first two links? The third link gives an opinion as to the size of various components of the Earth. That opinion is different from other websites. You wrote (in response to my opinion that surface "g" was 40-50% of what it is today: "Again. do you have any evidence for this? Your guess is not good enough and is based on false data as is pointed out in the link i provided." Which link is that? Specifically, what is the "false data." You wrote: "So far you have not given any evidence that this shift of 0.375% of the earths mass occurred or could have occurred much less that it would have changed the earths gravity." First of all, your statement is erroneous. Unless you are denying the formation of Pangea, this shift is well documented. It looks like you still don’t understand the conservation of angular momentum. You wrote (i n response to my explaining the global gravitational gradient): "Again you have shown no eviedence of this happening other than the size of the dinosuars which is false." The evidence is: 1. The unusually high sea levels near Pangea during the Phanerozoic. 2. The largest sauropods were only found in near equatorial regions, consistent with the proposed gravitational gradient. Again, the irrelevance of the size of dinosaurs is your opinion. You wrote: "then i have falsified your claims unless you have some evidence of your claims other than your guesses." Hardly! I would suggest you study the concepts of angular momentum, particularly the conservation thereof. Then explain what happened when Pangea formed (with the bulk of its mass moving south of the equator. If you can come up with an answer that doesn't involve movement of the core elements, then you might have falsified the claims I have made.
swansont Posted May 23, 2011 Posted May 23, 2011 ! Moderator Note Moved from http://www.scienceforums.net/topic/57018-gravity-affect-size/ This is clearly speculation and was a hijack of that thread. Earthling, I will remind you that the rules dictate that you back up your claims with evidence. Proof by repeated assertion impresses nobody. Hardly! I would suggest you study the concepts of angular momentum, particularly the conservation thereof. Then explain what happened when Pangea formed (with the bulk of its mass moving south of the equator. If you can come up with an answer that doesn't involve movement of the core elements, then you might have falsified the claims I have made. Like this. It is your burden of proof to show that the movement of the continents can lead to a reduction in gravity and by how much. Moontanman has shown adequate understanding of the concept of angular momentum. What is lacking is a convincing application of it on your part.
Ophiolite Posted May 23, 2011 Posted May 23, 2011 One could guess at "g" based on the size of the largest dinosaurs or largest pterosaurs....but this would only be a guess. Excellent news. Using this 'guess' we dicsover there is no difficulty whatsoever in having large dinosaurs and pterosaurs with our user friendly currently applied 981m/sec/sec. Can we now have a productive discussion on something more substantial?
michel123456 Posted May 23, 2011 Posted May 23, 2011 (edited) Excellent news. Using this 'guess' we dicsover there is no difficulty whatsoever in having large dinosaurs and pterosaurs with our user friendly currently applied 981m/sec/sec. Can we now have a productive discussion on something more substantial? I am not sure. I think that current g has been considered as an axiom, and is a corner stone for all reconstruction of ancient animals. Not that our knowledge of the ancient animals can be used to deduce an hypothetical g. --------------------------- Since the thread has been broken into pieces, just to make a reminder about the scale we are talking about. Also, IIRC, gigantism of early Earth is not only about dinosaurs, but about insects & plants as well. Some difficulty to find links though. Edited May 23, 2011 by michel123456
swansont Posted May 23, 2011 Posted May 23, 2011 A major problem with reducing g is you thin atmosphere, which is a problem for big things that fly
michel123456 Posted May 23, 2011 Posted May 23, 2011 A major problem with reducing g is you thin atmosphere, which is a problem for big things that fly Yes. Although force is the question, not g. One should make a complete model before jumping into conclusions. Maybe a slight change could have big effects, I don't know.
Earthling Posted May 24, 2011 Author Posted May 24, 2011 michel123456, Yes, there were other life forms that were huge in the distant past: http://www.bbc.co.uk/nature/life/Eurypterid The fossil remains of one of these was reported to be 8 feet long. Of, course, some people will attribute that to a host of reasons.......none of which will be lower surface gravity. Also, under the current theory, surface "g" was lower on Pangea (than current value) and higher (than current value) antipodally to Pangea. Therefore, "thinning of air" would have been mitigated or absent on this spinning planet.
michel123456 Posted May 24, 2011 Posted May 24, 2011 Yes. About insects i found this picture in this link from a blog. The text is a copy-paste of an article from Science-Daily you can find here. Here gigantism is explained through a change of ogyxen concentration in the atmosphere. I found nothing about plants. Still searching.
Earthling Posted May 25, 2011 Author Posted May 25, 2011 michel123456, I have read similar websites/articles about the giant dragonflies (Meganeuropsis permiana) and they also attribute their large size to higher oxygen levels. I seriously doubt (as you might expect) whether that is the primary reason why they attained their gigantic size. If they "made their living" in the same way extant dragonflies do, they would have to move at tremendous speed, in start and stop mode. This would generate a tremendous amount of heat in order to move an insect this size causing overheating......insects don’t have the muscle structure to dissipate heat. However, if its weight were half (or less), things would be less problematic. The same applies to the 10 pound frog (beelzebufo ampinga) of the Cretaceous. They can’t attribute its size to oxygen levels........so what could it have been and why did it go extinct?
Moontanman Posted May 25, 2011 Posted May 25, 2011 (edited) Moontanman, You wrote: "Dinosaurs and mammals both evolved at about the same time, dinosaurs were superior to mammals for at least two reasons, they had better respiratory systems and stronger bones, both of which allowed them to exploit larger body size better than other animals, no need for lower gravity. There is no evidence that animals the size of dinosaurs are impossible or even improbable at the surface gravity of today. If you think creatures the size of dinosaurs were impossible i suggest you give some evidence of this, current knowledge disagrees with you." Dinosaurs and mammals did not evolve at the same time. If you think dinosaurs that come close to the size of whales could live on land today, you are entitled to your opinion.....I will not ask you to prove that. Probably because you don't have a clue as to what dinosaurs were or how they evolved and there is no reason what so ever why land animals as large as dinosaurs could not live on land today, whales are not part of this discussion btw... and you have not shown any reason what so ever why land animals as large as dinosaurs couldn't live today any more than you've shown that gravity was lower during the time of the dinosaurs. The first true mammals appeared about 215,000,000 years ago, mammal like reptiles occurred many millions of years before the first true mammals as did the archosaurs which the dinosaurs evolved from, the first true dinosaurs appeared about 225,000,000 years ago, neither one was particularly larger than the other (although both groups did produce large animals) nor where they alone in there environment when they appeared and had to compete with many other types of land animals, since you do not seem to be compelled to give any source for your ravings neither will I.... Edited May 25, 2011 by Moontanman
Earthling Posted May 26, 2011 Author Posted May 26, 2011 Moontanman, No expert on dinosaurs am I but I probably know a little more about them than you do. Dinosaurs appeared about 230mya. They were held in check by the crurotarsans until the Triassic-Jurassic mass extinction. During that event, the crurotarsans (at least the largest of them) became extinct. Do you know why they became extinct? The GTME is the only theory that provides a reasonable explanation......which follows: The T-J extinction was the result of a major rapid increase in surface gravity. That increase was due to the major continental separation which started the opening of the Atlantic Ocean. Reread my prior posts if you don’t remember the relationship between continental movement and core element movement (and therefore changes to surface gravity). The crurotarsans had splayed legs, similar to extant crocodiles. Dinosaurs had legs similar to existing large mammals (i.e., they were straight beneath their bodies, not splayed). Which of the above two leg structures would be adversely affected by an increase in surface gravity?????? Yes, the splayed leg crurotarsans! That’s why the larger, terrestrial crurotarsans became extinct at that time while the smaller ones that inhabited bodies of water (like the crocodile) survived. Your statement: "Probably because you don't have a clue as to what dinosaurs were or how they evolved and there is no reason what so ever why land animals as large as dinosaurs could not live on land today....." This proves that it is you who have "no clue" about animal morphology. If I could post a life-size image of a Brachiosaurus next to a giraffe, you would eat your words. I would ask you to explain how blood was pumped to that dinosaur’s head when a giraffe has an oversized heart, special flesh membranes on its legs to deal with the high blood pressure, etc. Reasonable people would not support the belief that Brachiosaurus could exist today.
Earthling Posted May 27, 2011 Author Posted May 27, 2011 Moontanman, I went back to look at some of your postings. In one of them you wrote: "Dinosaurs and mammals both evolved at about the same time, dinosaurs were superior to mammals for at least two reasons, they had better respiratory systems and stronger bones, both of which allowed them to exploit larger body size better than other animals, no need for lower gravity." Your statement is contradicted by scientists who recently wrote a book about sauropods (‘Biology of the Sauropod Dinosaurs’). The NY Times wrote an article about this subject and here is what they wrote: "...scientists in the German-Swiss group proposed that sauropod bone had superior mechanical properties compared with large mammal bone, which would have given dinosaurs stronger skeletons to support their heftier bodies. The hypothesis was tossed aside after tests showed sauropod and cow bone tissue had the same strength." -1
Moontanman Posted May 27, 2011 Posted May 27, 2011 (edited) Moontanman, I went back to look at some of your postings. In one of them you wrote: "Dinosaurs and mammals both evolved at about the same time, dinosaurs were superior to mammals for at least two reasons, they had better respiratory systems and stronger bones, both of which allowed them to exploit larger body size better than other animals, no need for lower gravity." Your statement is contradicted by scientists who recently wrote a book about sauropods (Biology of the Sauropod Dinosaurs). The NY Times wrote an article about this subject and here is what they wrote: "...scientists in the German-Swiss group proposed that sauropod bone had superior mechanical properties compared with large mammal bone, which would have given dinosaurs stronger skeletons to support their heftier bodies. The hypothesis was tossed aside after tests showed sauropod and cow bone tissue had the same strength." So you claim, so what! I claim I am god so what! Give us some sources to show your claim is better than mine.... Edited May 27, 2011 by Moontanman
michel123456 Posted May 27, 2011 Posted May 27, 2011 (edited) I went on digging for more information. With the idea that gravity is suspected to have changed, I searched for traces. A footprint of T-REX has been found in 1984 in New Mexico (identified though disputed). The following is an attempt to put it to scale in relation to a large existant animal, the elephant: area calculation has been done after putting pictures to scale in Cad programm. _An average indian elephant weights 4160 kgs to 5400 kgs _Current accepted estimation of T-Rex weight ranges from 5400 kgs to 6800 kgs By simple calculation we get 1.for the 4 legged elephant low value 4160kg / (0,122m2 x 4) = 8254 kg/m2 large value 5400kg / (0,122m2 x4) = 11065 kg/m2 which is an approximation of the pressure exerted on the soil by an equal repartition of its weight on 4 feets. 2. for the bipedal T-Rex low value 5400kg / (0,289m2 x2) = 9342 kg/m2 large value 6800kg / (0,289m2 x2) = 11764 kg/m2 Although with a lot of cumulated approximations, the result shows that pressure exerted by the 2 feets of T-rex is quite close to that of the elephant. Which is a good point for existing knowledge and very bad for the "lower gravity speculation". Of course, one could argue that T-rex identification was based upon the same principle, making all the above a circular argument. But that is over my head. I leave the field for specialists. sources http://en.wikipedia.org/wiki/Tyrannosaurus http://esp.cr.usgs.gov/info/kt/footprint.html http://www.amnh.org/exhibitions/dinosaurs/theropod/walk.php http://en.wikipedia.org/wiki/Indian_Elephant this image Edited May 27, 2011 by michel123456 4
imatfaal Posted May 27, 2011 Posted May 27, 2011 Michel - from a quick look at the literature I think your reasoning is good and not circular. the mass of T-Rex is estimated from far more than the print size; among those factors considered bone mass, muscle mass (estimated from tendon attachments on bone), toothsize (from marks on prey) and even poo-size (A king-sized theropod coprolite. Nature 393, 680−68)
michel123456 Posted May 27, 2011 Posted May 27, 2011 Michel - from a quick look at the literature I think your reasoning is good and not circular. the mass of T-Rex is estimated from far more than the print size; among those factors considered bone mass, muscle mass (estimated from tendon attachments on bone), toothsize (from marks on prey) and even poo-size (A king-sized theropod coprolite. Nature 393, 680−68) what i found in the litterature is that current estimations may be over-estimated. If that is correct, the calculation should be redone with a lighter T-Rex, very very bad for speculations about low gravity. Too bad, I liked the idea.
michel123456 Posted May 27, 2011 Posted May 27, 2011 After some deeper thought, maybe it is incorrect to compare a T-rex with an elephant. The one is a terrible running predator, the other is a nonchalant vegetarian. Since I am not aware of any current bipedal predator comparable to T-rex, maybe the ostrich would be the best candidate.
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