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Science/Tech See other Science/Tech Articles Title: Dinosaurs say: Gravity was weaker in the past! THE IMPOSSIBLE DINOSAURS Ted Holden A careful study of the sizes of the giant dinosaurs creatures and of what it would take to deal with such sizes in our world, the felt effect of gravity being what it is now, indicates that something was massively different in the world which these creatures inhabited. A look at sauropod dinosaurs as we know them today requires that we relegate the brontosaur, once thought to be one of the largest sauropods, to welterweight or at most middleweight status. Fossil finds dating from the 1970's dwarf him. The Avon field Guide to Dinosaurs shows a brachiosaur (larger than a brontosaur), a supersaur, and an ultrasaur juxtaposed, and the ultrasaur dwarfs the others. Christopher McGowan's "Dinosaurs, Spitfires, & Sea Dragons", Harvard, 1991 cites a 180 ton weight estimate for the ultrasaur (page 118), and (page 104) describes the volume-based methods of estimating dinosaur weights. McGowan is Curator of Vertebrate Paleontology at the Royal Ontario Museum. This same look requires that dinosaur lifting requirements be compared to human lifting capabilities. One objection which might be raised to this would be that animal muscle tissue was somehow "better" than that of humans. This, however, is known not to be the case; for instance, from Knut Nielson's, "Scaling, Why is Animal size So Important", Cambridge Univ Press, 1984, page 163, we have: "It appears that the maximum force or stress that can be exerted by any muscle is inherent in the structure of the muscle filaments. The maximum force is roughly 4 to 4 kgf/cm2 cross section of muscle (300-400 kN/m2). This force is body-size independent and is the same for mouse and elephant muscle. As creatures get larger, weight, which is proportional to volume, goes up in proportion to the cube of the increase in dimension. Strength, on the other hand, is known to be roughly proportional to cross section of muscle for any particular limb, and goes up in proportion to the square of the increase in dimension. This is the familiar "square-cube" problem. The normal calculation for this is to simply divide by 2/3 power of body weight, and this is indeed the normal scaling factor for all weight lifting events, that is, it lets us tell if a 200 lb athlete has actually done a "better" lift than the champion of the 180 lb group. Consider the case of Bill Kazmaier, the king of the power lifters in the seventies and eighties. Power lifters are, in the author's estimation, the strongest of all athletes; they concentrate on the three most difficult tota -body lifts, i.e. benchpress, squat, and dead-lift. They work out many hours a day and, it is fairly common knowledge, use food to flavor their anabolic steroids with. No animal the same weight as one of these men could be presumed to be as strong. Kazmaier was able to do squats and dead lifts with weights between 1000 and 1100 lbs on a bar, assuming he was fully warmed up. STANDING UP AT 70,000 LBS Any animal has to be able to lift its own weight off the ground, i.e. stand up, with no more difficulty than Kazmaier experiences doing a 1000 lb squat. Consider, however, what would happen to Mr. Kazmaier, were he to be scaled up to 70,000 lbs, the weight commonly given for the brontosaur. Kazmaier's maximum effort at standing, fully warmed up, assuming the 1000 lb squat, was 1340 lbs (1000 for the bar and 340 for himself). The scaled maximum lift would be a solution to: 1340/340^.667 = x/70,000^.667 or 47,558 lbs. That is to say, the maximum weight his muscles could lift when scaled to the size of an Brontosaur would be 47,558 lbs. If he weighed 70,000 lbs, he'd not be able to lift his weight off the ground! To believe then, that a brontosaur could stand at 70,000 lbs, one has to believe that a creature whose weight was largely gut and the vast digestive mechanism involved in processing huge amounts of low-value foodstuffs, was somehow stronger than a creature its size which was almost entirely muscle, and far better trained and conditioned than would ever be found amongst grazing animals. That is not only ludicrous in the case of the brontosaur, but the calculations only get worse when you begin trying to scale upwards to the supersaur and ultrasaur at their sizes. Another way to look at the problem of size vs. strength under present Earth gravity is to ask- how heavy can an animal get to be in our world? How heavy would Mr. Kazmaier be at the point at which the square-cube problem made it as difficult for him just to stand up as it is for him to do 1000 lb squats at his present size of 340 lbs? The answer is simply the solution to: 1340/340^.667 = x/x^.667 or just under 21,000 lbs. In reality, elephants do not appear to get quite to that point. McGowan (Dinosaurs, Spitfires, & Sea Dragons, p. 97) claims that a Toronto Zoo specimen was the largest in North America at 14,300 lbs. One has no difficulty visualizing the slow, lumbering, weight encumbered movements of elephants. Clearly they are operating at the limits of biological size. Even the scaling up of the Rhinoscerous, as the popular Paleontoligist Bob Bakker is fond of doing in defense of sauropod mobility, would run you straight into the scaling formula cited above, independent of leg length proportions. Again, in all cases, we are comparing the absolute maximum effort for a human weight lifter to lift and hold something for two seconds versus the sauropod's requirement to move around and walk all day long with scaled weight greater than these weights involved in the maximum, one-shot, two- second effort. That just can't happen. SAUROPOD DINOSAUR'S NECKS A second category of evidence for attenuated felt effect of gravity arises from the study of sauropod dinosaurs' necks. Scientists who study sauropod dinosaurs are now claiming that they held their heads low, because they could not have gotten blood to their brains had they held them high. McGowan (again, Dinosaurs, Spitfires & Sea Dragons) goes into this in detail (pages 101-120). He mentions the fact that a giraffe's blood pressure, at 200-300 mm Hg, far higher than that of any other animal, would probably rupture the vascular system of any other animal, and is maintained by thick arterial walls and by a very tight skin which apparently acts like a jet pilot's pressure suit. A giraffe's head might reach to 20'. How a sauropod might have gotten blood to its brain at 50' or 60' is the real question. Two articles which mention this problem appeared in the 12/91 issue of Natural History. In "Sauropods and Gravity", Harvey B. Lillywhite of Univ. Fla., Gainesville, notes: "...in a Barosaurus with its head held high, the heart had to work against a gravitational pressure of about 590 mm of mercury (Hg). In order for the heart to eject blood into the arteries of the neck, its pressure must exceed that of the blood pushing against the opposite side of the outflow valve. Moreover, some additional pressure would have been needed to overcome the resistance of smaller vessels within the head for blood flow to meet the requirements for brain and facial tissues. Therefore, hearts of Barosaurus must have generated pressures at least six times greater than those of humans and three to four times greater than those of giraffes." In the same issue of Natural History, Peter Dodson ("Lifestyles of the Huge and Famous"), mentions that: "Brachiosaurus was built like a giraffe and may have fed like one. But most sauropods were built quite differently. At the base of the neck, a sauropod's vertebral spines unlike those of a giraffe, were weak and low and did not provide leverage for the muscles required to elevate the head in a high position. Furthermore, the blood pressure required to pump blood up to the brain, thirty or more feet in the air, would have placed extraordinary demands on the heart and would seemingly have placed the animal at severe risk of a stroke, an aneurism, or some other circulatory disaster. If sauropods fed with the neck extended just a little above heart level, say from ground level up to fifteen feet, the blood pressure required would have been far more reasonable." It turns out that a problem every bit as bad or worse than the blood pressure problem would arise, perceived gravity being what it is now, were sauropods to hold their heads out just above horizontally as Dodson and others are suggesting. Try holding your arm out horizontally for more than a minute or two, and then imagine your arm being 40' long and 30,000 lbs... An ultrasaur or seismosaur with a neck 40'-60' long and weighing 25000-40000 lbs, would be looking at 400,000 to nearly a million foot pounds of torque were one of them to try to hold his neck out horizontally. That's crazy. You don't hang a 30,000 lb load 40' off into space even if it is made out of wood and structural materials, much less flesh and blood. No building inspector in America could be bribed sufficiently to let you build such a thing. And so, sauropods (in our gravity) couldn't stand, couldn't hold their heads up, couldn't hold them out either. Moreover, the fossil record shows that there were a large number of "giant" species- giant insects, giant mammals such as a beaver the size of a kodiak bear, giant fish and flying creatures that have not survived into our present era. The only way of making sense out of this evidence is to understand that at one time and for whatever reason, the force of gravity operated differently on planet Earth.
Poster Comment: Why aren't there any big creatures anymore? All of them used to be huge -- bugs, mammals, dinosaurs. All gone? Why?
Post Comment Private Reply Ignore Thread Top • Page Up • Full Thread • Page Down • Bottom/Latest Begin Trace Mode for Comment # 15.
#1. To: YertleTurtle (#0)
They probably lived in marshes and swamps where the water buoyed them up. Like a hippo does today. This would also explain the blood pressure problem.
T-Rex didn't live in a swamp. Most dinosaurs did not. Swamps don't explain the enormous size of everything back then, including sea creatures. There are no creatures today anywhere near the size of prehistoric ones. What is the difference between then and now that prevents modern creatures from growing to the size of those in the past?
T-Rex wasn't much bigger mass wise than an elephant. Most other dinosaurs were not as big as the giant sauropods either. If you look at that fiberglass mockup in front of the natural history museum in San Diego it's obvious that it's an aquatic creature. It's basically a snake with tiny (by comparison) vestigial legs. It's all tail and neck with a bump in the middle that is the body.
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