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Dinosaurs not fat, but big boned

By Mike, 30 October 2012 News

Sauropod and human

Guessing the weight of a dinosaur isn’t a simple task.
Image: Thinkstock

Written by Emma Bastian

How do you weigh a dinosaur? It’s a simple question with a very complex answer.

Dinosaurs didn’t leave much of their bodies behind. Aside from footprints and some impressions of their skin and feathers, most dinosaur remains are the fossils, or  casts, of bones. Since the bone has been replaced by other minerals, dinosaur casts are much heavier than their bones would have been. Now, scientists have come up with a new way of calculating a dinosaur’s weight using fossils.

British scientists used a laser scanner to measure the minimum amount of skin it would take to wrap around the skeletons of modern animals such as giraffes, elephants and polar bears. They then compared these ‘skin and bones’ measurements to the animals’ actual body weights.

The estimations and the actual body weight differed by nearly 21 percent for all the different animals. The scientists then applied this method to a Brachiosaur skeleton. Based on this, they figured the Brachiosaur once weighed approximately 23 tonnes, compared with  previous guesses of about 80 tonnes.

Knowing the weight of a dinosaur is important for palaeontologists, because it means they can better understand not only what a dinosaur looked like, but how they moved. Could they run, walk or maybe even fly? Well a 23-tonne Brachiosaur still isn’t light enough to get off the ground, but it is looking a lot trimmer these days.

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4 comments

  1. Reblogged this on News @ CSIRO and commented:

    How heavy was a Brachiosaur? Why is A4 paper the size that it is? Our new blog, Helix @ CSIRO, has all the answers. For the young and young at heart.

      Reply
  2. I would only like to comment that the statement “A 23 ton Brachiosaur still isn’t light enough to get off the ground” is rather over stepping the bounds of the supplied data. The 747-8 jumbo can take off with just shy of 440tons, so clearly weight isn’t the issue. You of course know that, but I think writing for developing minds you should choose words more wisely 🙂

    BTW, another method that can be used to determine weight (of land animals at least) is looking at the hard area of the foot, apparently the ratio of weight to contact area holds true from elephants to gazelles.

      Reply
    1. The ratio of strength to weight falls off as size increases. This places severe limits on the mass of a flying animal. I think that it is quite safe to say that a 23 ton animal cannot fly — unless it is cargo in a flying machine.

      The same scaling puts a limit on the mass of an animal if that animal is to be capable of supporting itself against the force of gravity.

        Reply
  3. Thanks for the reply Max, and you’re dead on. Technically a brachiosaur could fly, given the right wingspan and velocity. Not to say I’d want my car under its flight path.

    While it was a bit of a throw away line, you’ve made a good point. Thanks again.

      Reply

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