Sauropods, Elephants, Weightlifters
Miscellaneous Issues
by Wayne ThroopCopyright © 1995-2003
[Text Last Updated: June 27,
1995]
[Links Updated: March 27, 2003]
Again, in all cases, we are comparing the absolute max 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.This claim of Ted's is simply a consequence of improper use of square-cube scaling. It is true that available muscle force isometrically scales by square-cube ratio, but endurance or power does not. From Ted's own source on the uniformity of muscle strength per cross section, Knudt Nielson points out on page 164 of [WASI] that
[...] the work required to move 1kg of animal over a given distance decreases with increasing body mass.This in turn is due to the fact that the work done is force-times-distance, and distance increases as cube-root of mass. Thus, work or effort does NOT square-cube scale, and even if a larger animal approaches the limits on force their muscles can apply, they need not at the same time be approaching endurance limits that a smaller animal would be.
Thus, the notion that a sauropod dinosaur would have endurance problems (that is, problems "walking around all day") is false. In fact, we can already see that Ted's notion of endurance problems is implausible, since even modest-sized elephants are walking around "all day" that weightlifters could only manage for minutes at a time. That is, Ted's comparison formula says that an elephant of 6 tons is equivalent to Kazmaier with about 800 lbs.
Even using all muscles, some more than once, the strongest man who we know anything about would not be able to lift his own weight off the ground at 70,000 lb.!The "using muscles more than once" if we correct for 2-to-4 limbs between Kazmaier and a sauropod is a matter of using muscles in series vs in parallel. In no relevant way is a muscle being "counted twice". Further, in the structural arguments advanced here, there is no such dual accounting at all.Moreover, Kazmaier is using gluteal and lower back muscles in the squat, and pectorals in the benchpress, i.e. extra muscle groups which the sauropod he is being compared to would not be assisted by in standing.
The issue of "gluteal and lower back muscles [and] pectorals" is simply inaccurate. Sauropod dinosaurs had the equivalent muscle groups. True, in the analyses done here, I've concentrated on the knee joint and the muscles that drive it. But that doesn't mean the other joints weren't driven by their corresponding homologous muscles.
And from Ted's megafauna pageFrom: medved@access1.digex.net (Ted Holden) Message-ID: <medved.780880048@access1> 450,000 (roughly) ft. lbs. which the ultrasaur needs to manage while holding his neck out horizontally as scientists are now claiming he had to do.
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.Now, which scientists claim this? Ted likes to quote Lillywhite and Dodson from the December 1991 "Natural History" magazine. But Dodson, in the text Ted quotes of him, states quite clearly "Brachiosaurus was built like a giraffe, and may have fed like one." So Dodson clearly does not think it was impossible.
How about Lillywhite? His article doesn't contain an unambiguous statement like Dodson's, but as it turns out, an officemate of mine knows Lillywhite personally, and he arranged to introduce us by phone. I asked Lillywhite whether he thought the vertical head posture was impossible in brachiosaurs, and he said he did not. He said his main point in that article was to discuss the physiological implications of the vertical neck posture, not to rule it impossible. In fact, he reminded me of this bit in the article:
Lillywhite, "Sauropods and gravity", Natural History, Dec '91 p33
Roger Seymour estimated the heart size of a large, erect sauropod to have been more than 1.6 metric tons, or eight times heavier than that of a similar-sized whale having a comparable internal heart volume. This may be an overestimate, however, because the structure of reptilian hearts allows a smaller wall thickness for a given stress then does a mammalian heart. Nonetheless, in most large dinosaurs, the ribs around the heart are long, suggesting that the cardiac compartment was indeed capacious.
The interesting point being, most of the physiological consequences or adaptations to high blood pressure are in soft tissues, and can't be checked. But one prediction of high blood pressure is an enlarged heart, and there is skeletal evidence of just such an enlargement. Far from saying it was impossible, Lillywhite was saying that at least one of the adaptations required for an erect posture seems possible, and consistent with skeletal evidence.
Alexander says
Alexander, "Dynamics of Dinosaurs and other Extinct Giants", p62Note: a "very muscular heart", which Lillywhite points out evidence for. Bakker points out similar evidence in [tDH] on page 364, with an accompanying diagram.
It would be a mistake to argue that a blood pressure of 8.5 meters of water would be impossible, because it is so much higher than the blood pressures of modern animals. If giraffes were unknown, that kind of argument would lead to the conclusion that giraffes are impossible. However, the blood pressure calculated for Brachiosaurus does seem remarkable, and a very muscular heart would have been needed to produce it.
Even McGowan only says that
McGowan, "Dinosaurs, Spitfires and Sea Dragons", p120Note well, he never says that a four-footed erect-headed stance can be ruled out, and "serious problems" does not equal "impossible".
The idea that sauropods reared upon their hind legs, raising their heads even higher than their necks allowed, can be dismissed on grounds of blood pressure alone. Even holding their heads as high as in most mounted skeletons would have presented serious problems.
So, Ted's assertion that "scientists are now claiming" that all sauropods must have held their necks low is not very accurate. The consensus is fairly clearly that diplodocids held their necks out horizontally, and brachiosaurids held their necks vertically. And this position, far from being a "dilemma" as Ted claims, isn't even a "monolema". Neither vertical head posture, nor horizontal head posture were impossible, in biomechanical terms.
But this whole line of argument is easily falsified. Consider a whole range of creature size, from ant to cat to elephant. An ant, even though if it can lift a hundred times its weight, has a Holden Number of only about 5, the cat of perhaps between 10 and 20, and an elephant of at least 25.From: medved@access1.digex.net (Ted Holden) Message-ID: <310o3e$35@access1.digex.net> As creatures get bulkier, they become less efficient; the layers of thick muscle in limbs begin to get in each others way and bind to some extent. For this reason, scaled lifts for the super-heavyweight athletes are somewhat lower than for, say, the 200 lb athletes.
The point being, square-cube corrected performance increases as animals get more massive. How then to account for the fact that performance falls off in heavier weightlifting classes? Since performance falls off in a very similar way in the lighter classes, it becomes clear that this reflects a simple statistical sampling phenomenon: there is a smaller pool of heavier-than-average and lighter-than-average people from which to draw competitors, and so performance trails off at extremes of body size away from human averages. But this only applies to human atheletes, and in totally irrelevant in attempting to project performance cross-species, especially over such a large size range as human-to-sauropod.
Ted quantifies the sauropod's disadvantage here as 3-to-1. Yet elephants also are "mostly gut and digestive system for processing leaves and other low-value foods" in the same sense that sauropods are, so Ted's 3-to-1 disadvantage next to Kazmaier would also apply to them, if it were a valid point. Yet even very small elephants are far larger than 3-to-1 weaker than Kazmaier would allow for. Using Ted's own methods, solve forFrom: medved@access5.digex.net (Ted Holden) Message-ID: <medved.803649615@access5> A sauropod dinosaur standing next to Kazmaier at the same weight, would be seen to have something like a third of the available musculature. Kaz lives at the top of the food chain, and is mostly muscle; the saur lives at the bottom, and his body is mostly gut and digestive system for processing leaves and other low-value foods.
((1340/340^(2/3))*(1/3)) = x/x^(2/3) = x^(1/3)and we find that elephants would be restricted to being quite a bit less than a thousand pounds if they were at such a disadvantage.
Ted's whole argument is based on uniformity of muscle tissue, and yet he is claiming that elephants somehow manage to nearly equal Kazmaier's performance (at least 80% of it) with only a third of the "available musculature". Ted has absolutely no rationale for any claim that something he himself insists elephants do, the sauropods couldn't do a bit better.
[weightlifters] 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.This line of argument is irrelevant, because Hokkanen's analysis doesn't project from human weightlifter performance, the structural arguments I've presented here start from performance levels far below those requiring steroids also.
Even if not irrelevant, Ted has no way of knowing that sauropods didn't produce steroids naturally in greater quantities than humans do naturally. Anabolic steroids and HGH and other factors that promote growth and muscle mass are all based on naturally occuring compounds.
McGowan, Bakker, and Gillette all comment on this issue, and provide reasons why such large sizes are no longer favored.
McGowan, Bakker and Gillette point out that sauropods had gizzards, which elephants do not have. And in [E&TH] the comment is made in discussing nutrition and growth that in elephants, statistics on size "indicate that food is limiting".
Further Bakker points out that in unstable climates, large sizes are a disadvantage, because of the longer generation times and lower rates of adaptation, and vulnerability to feast/famine cycles.
Thus, the long, stable, ecologically productive climate of the Triassic and Jurasic, a stability lasting several times longer than the period since, were very plausibly the unique ingredients that are missing in today's world.
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