The Biggest Loser

It’s not easy being extinct. Case in point: — the Giraffatitan. Lost its family (used to be considered the African version of the brachiosaurus.) Lost its claim as the largest dinosaur known (to three species of titanosaurians). Now it’s lost 61 tons!

The traditional method of estimating dinosaur mass was to measure the circumference of leg bones, compare that with the circumference in modern animals, and scale up the result to the size of a dinosaur. These calculations were simplified by modeling leg bones as columnar beams – which may have underestimated the stresses experienced in animal limbs by up to 142 percent.

Researchers have been at work on a new and more accurate system of mass prediction. The new method shows Giraffatitan’s body massed only 25 tons – dramatically less than in previous estimates, which ranged from 31 to 86 tons.

Twenty five tons – 50,000 pounds? That’s not even half the weight aboard the average illegally-loaded tractor-trailer riding an Ohio interstate on its way to Michigan!

5 thoughts on “The Biggest Loser

  1. I thought the way you weigh a dinosaur is to make a scale model of it, and measure how much water it displaces. If you make a 2-ft-long model of a 50-ft-long dinosaur, with all the other dimensions in proportion, then the actual dinosaur would displace 25-cubed or 15,625 times the weight of water displaced by the model, or not quite 8 tons per pound of water displaced, or 64 tons per (US) gallon displaced, assuming that, in common with most animals, the average specific gravity is 1 or slightly less, i.e., that the animal would float. I seem to remember seeing this demonstrated on one of the science programs on TV not so very long ago. This article from the British newspaper the Guardian may be of interest:

    But it seems there are a number of ways of estimating dinosaurs’ weight, including the femur-measurement described.

    I understand that that most recent research suggests that dinosaurs didn’t weigh as much as we had thought, as your article describes.

  2. That would only work for dinosaurians living near the equator … and the difference could be measured in under an ounce, unless the Earth rotated at a substantially more rapid speed. Not a 23 hour day. Not an 18 hour day. A seven-and-a-half minute day might suffice to remove 61 tons from the scales, though. Hard to say, but some of the geekier readers have already leaped to their calculators to work it out. Of course, those Antarctic dinosaurs would end up correspondingly heavier, for being closer to the center of the Earth than if the planet were a perfect sphere. One can imagine velociraptors the size of a Smurf that weighed in at 45 pounds. But, wait … they’d have leg bones as thick through as my thumb as well. I smell a joke…

  3. Sam, those model-based displacement studies are OK for certain purposes but they assume that the dinosaurs were all solid all the way through. There’s evidence of extensive airsac systems in some forms, such as you find in birds – especially in the bigger dinosaurs like Girrafatitan. Extrapolation from a solid model will lead you wildly off.

  4. Lars, you’re right. The displacement method I mentioned is just a first approximation. But I understand there are now methods available to paleontologists that can take into account differences in tissue density, including bones and air sacs and presumably even feathers.

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