New research provides clear answer to debate on dinosaur posture

Feb 23, 2012
Drawings by Shin-ichi Fujiwara (drawing grayscale image) and Soichiro Kawabe (coloring) from the University of Tokyo

(PhysOrg.com) -- Research published today (22nd February) provides, for the first time, a clear answer to the debate as to whether Triceratops and other extinct creatures took on a more mammal-like or more reptile like posture.

Dr. Shin-ichi Fujiwara from the University of Tokyo and Professor John Hutchinson from the Royal Veterinary College have developed a new, advanced method that provides insight into the kinds of forelimb postures might use, derived from simple measurements on bones.

Findings using the new method show that, contrary to popular belief, Triceratops had quite upright forelimbs like larger mammals, not splayed out to the sides like most reptiles and amphibians. This understanding changes the way we visualise the posture and motion of , and also suggests that the animal might have been more athletic than previously thought.

Different use different muscles to support their weight, which attach to different bones in the elbow. Because of this Fujiwara and Hutchinson concluded that the bones must be shaped differently to form competent levers for the attaching elbow muscles.

Upright animals (e.g. dogs, cats, elephants, ) favour their triceps muscles and as a result have a large 'funny bone', or olecranon process, to act as an efficient lever for those muscles to keep the elbow from flexing too much. In contrast sprawling animals (e.g. lizards, , frogs, ) favour their adductors (muscles that pull the elbow to the body) to keep the elbows from splaying too far out laterally.

To test their ideas the researchers measured the elbows of 318 different skeletons and found that three main measurements captured the complexity of elbow joint support in animals. Dr. Fujiwara remarked: "I travelled to museums around the United Kingdom and Japan to measure every animal specimen I could find. It was weeks and weeks of measuring skeletons but was worth it! We were able to develop a massive database for testing our hypotheses."

Professor Hutchinson commented: "We've developed a new method for reconstructing forelimb postures that is statistically rigorous and numerical, rather than relying on hazy value judgements based on intuitive impressions from anatomy. It is also based on real, established mechanisms of locomotor biomechanics that diverse animals use today, linking bone form and function. It thus packs a potent explanatory power, rather than arguing from correlation equals causation. That's a satisfying step forward and a leg up on prior methods."

The next step, the researchers say, is to apply this method to other extinct animals including various large dinosaurs and mammals to examine how giant animals supported their weight similarly or differently during their evolution.

The research is published in the Royal Society Journal Proceedings of the Royal Society B on the 22nd February 2012.

Explore further: New hadrosaur noses into spotlight

More information: Fujiwara, S; Hutchinson, J, Elbow joint adductor moment arm as an indicator of forelimb posture in extinct quadrupedal tetrapods , Proc. R. Soc. B; published ahead of print February 22, 2012, doi:10.1098/rspb.2012.0190

Provided by Royal Veterinary College

3.8 /5 (19 votes)

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Digi
5 / 5 (9) Feb 23, 2012
'Findings using the new method show that, contrary to popular belief, Triceratops had quite upright forelimbs like larger mammals, not splayed out to the sides like most reptiles and amphibians'

Well I for one assumed the popular belief was they did look like larger mammals ie more upright.
tadchem
5 / 5 (7) Feb 23, 2012
Biomechanically it makes far more sense for a massive body to be supported by legs that use rigid bones as pillars, than to rely on tensed muscles that would be prone to fatigue (pun intended).
Anda
4.7 / 5 (6) Feb 23, 2012
Contrary to popular belief????????? Nonsense...

I agree with you Digi. And Tadchem provides the explanation. That's not new.
Mercury_02
5 / 5 (4) Feb 23, 2012
Yeah, what popular belief? Every skeleton on display around the world has an upright posture.
eximago
5 / 5 (2) Feb 23, 2012
While it's definitely clear that the sprawled posture was not the popular opinion as the article states, it's good to see that we do have more hard evidence to support the upright hypothesis, though I honestly think that conjecture through mere observation of the limb bones was solid enough for me. Comparing pictures of a Triceratops arms to those of a mammal and to an alligator leaves an obvious impression, though it seems the upright stance wasn't as advanced in Triceratops. I wish the article was more specific in confirming or denying the latter part.
alanborky
1 / 5 (1) Feb 25, 2012
It depends on whose popular belief.

Maybe the popular belief concerned's Japanese - it sure ain't Western.

This might just be an example though of a trend growing in science for a while now which I call Barnum-ing ie instead of merely reporting something like say: "latest measurements confirm elephants stand and walk upright" scientists and science journalists big things up: "whereas dumb know-nothing schmucks everywhere actually thought elephants walked round on their heads or slithered along on their backs new research has found out they actually stand and walk upright" which a lot of science obsessive types actually buy into: "Ye' those dumb know-nothing schmucks!"

But if nothing else it gets a lot of WTF type attention.
Callippo
5 / 5 (2) Feb 25, 2012
Well I for one assumed the popular belief was they did look like larger mammals ie more upright.
You couldn't sell any of your publication with such an approach. You should always make your results as bombastic and fantastics as possible, because there is a huge overemployment in the world of science already. Whats better, such approach fits well with the attitude of journalists, who need to earn some money as well and the boring results are boring.

http://www.youtub...FC5ztSao

All triceratops reconstructions which I know have upright postures. The normally thinking people guessed instinctively, the reptile like posture couldn't maintain weight of this huge body.