New Analysis Shows Dinosaurs Not As Heavy As Previously Believed.

Cognitive Dissident writes "Discovery.com has an article on a new study using computer modeling to estimate the actual amount of flesh needed to cover the skeletons of dinosaurs. Based on a comparison with modern animals, it indicates that these animals could have weighed dramatically less than has been previously estimated. 'A huge Brachiosaur, once thought to weigh 176,370 pounds, is now believed to have weighed 50,706 pounds.' That's only about two-and-a-half times the weight of a modern African elephant. If other evidence can be reconciled with this, many estimates of the ecosystems dinosaurs lived in will also have to be revised."

Not necessarily

[Opyros]

This write-up [discovermagazine.com] gives reasons for doubting that the new technique does show dinosaurs were significantly lighter than previously thought.

Accuracy of estimate?

[rossdee]

"A huge Brachiosaur, once thought to weigh 176,370 pounds, is now believed to have weighed 50,706 pounds."

Those figures seem to imply they knew the weight to an accuracy of a few pounds, why don't they 175,000 and 50,000 pounds?

Did they measure the depth of the footprints?

While we are mentioning dinosaurs, a sad farewell to the Author of "A Sound of Thunder" Rest in Peace Ray

Re:Elephant metric system

[Anonymous Coward]

Even when talking "sience", there's nothing wrong with using pounds and ounces.
This is a US site, and science-savvy Americans understand both systems of units.

Re:Accuracy of estimate?

[quacking duck]

Because the original weights were in kilograms (80,000kg and 23,000kg respectively), and Discovery helpfully converted to the Imperial system for its American audience without properly sourcing the original figures.

Dear discovery channel,

[lurgyman]

When you converted 80,000 kg and 23,000 kg to pounds, it was swell of you to convert 1-2 significant digits to 5. I for one enjoy the round-off noise in the last 3 decimal places - it has premium aesthetic value. I bet those dinos probably thought the same way; losing weight must have been less depressing in terms of losing 2 pounds rather than 0.001%. On second thought, I barely know my own weight to 3 digits...

Precision

[Convector]

The masses given equate to 80000 kg and 23000 kg respectively. Or 80 and 23 (metric) tons. Two significant figures. Not more. No doubt those were the numbers originally supplied by the scientists, and the author of TFA converted it to pounds for the typical American reader without understanding how precision works. This happens all the time in the popular press. Clearly you can't estimate the weight of a creature you've never seen to within 1 lb. Your standard human's weight fluctuates by more than that over the course of a day.

Re:60s "science"?

[Chris Burke]

Off by a factor of 3 1/2 seems ridiculous, even if we're talking research that was done in the 60s.

I don't think that research was done in the 60s, and I certainly don't think this is up-ending the previous best estimate by such a large factor. I'd bet that guess was made closer to the time Brachiasaurus was discovered in the very early 1900s, and that's why it says "once thought" and "estimates have been as high".

WP suggests the most recent estimate (from 2009) was 28.7 metric tonnes.

While this new figure is still appreciably lighter, it doesn't make it sound as shocking to use the most recent estimate as the comparison point, does it?

Re:What about footprints?

[wvmarle]

I doubt a footprint can give any useful measure of the weight of the animal that made it.

Too many variables. Walking speed and method will influence it, as it affects the impact between foot and soil and the time the foot is pushing down on the soil. Exact original soil content (water content and particle size). How deep the soft layer of soil really was.

Re:And geeks wonder why Joe Six-pack disbelieves..

[Chris Burke]

10/10 for using the ol' "science is like Religion because they claim to have Truth and banish those who disagree with their Orthodoxy" line in an article about scientists at a major research university up-ending the "orthodoxy" and publishing their "heresey" in a Royal Society publication. I love this kind of irony.

Re:Elephant metric system

[Onkel Ringelhuth]

> You don't see ten meter-kilograms of torque listed in a technical manual anywhere across the globe, do you?
Nope. The unit is Newton-metres. Now, does anybody want to argue about standardisation of spelling?

Re:Not necessarily

[flyingsquid]

The 80,000 kg estimate has long been thought to be wildly inflated, and that estimate comes from a study published in 1962. A more recent estimate, published in 1997, gave a mass of 31500 for the Berlin brachiosaur, and a study published in 2009 estimated the mass of this specimen at 23000 kg... just 300 kg more than this study. So they haven't actually shaved off much weight with this latest version. It is an interesting new technique, if you have a skeleton to work with. But it's not terribly practical. Only a handful of dinosaurs are complete enough to make skeletal mounts and have actually been mounted. And we already have ways to estimate their mass- either make a model and dunk it in water to figure out the displacement (a method that's been around since the time of Archimedes) or use the diameters of the limb bones to estimate mass (as load-bearing structures, limb bone dimensions are very tightly correlated to total mass). It's nice to see previous estimates verified, and to have some constraints on how much meat to add onto the skeleton, but I don't think this technique is as big an advance as the authors claim.