Muscle reconstruction reveals how dinosaurs stood

Jun 21, 2012
Muscle reconstruction reveals how dinosaurs stood
Illustration of Centrosaurus. This dinosaur was a ceratopsid and Museum scientists have shown that this group stood with their front limbs bent outwards at the elbow. © Anness Publishing Ltd / The Natural History Museum

(Phys.org) -- Much is known about the dinosaurs that walked on 4 legs like Stegosaurus and Triceratops, but their stance has been a topic of debate, until now. Scientists at the Natural History Museum have revealed how these dinosaurs stood for the first time, and report their findings today.

Museum dinosaur experts Susannah Maidment and Paul Barrett reconstructed the muscles on dinosaur and combined this with what is already known about their skeletons to get a truer picture of how they stood.

The team looked at the (ceratopsids), the armoured dinosaurs (stegosaurs), and the duck-billed dinosaurs (hadrosaurs), 3 groups of ornithischian dinosaurs.

They studied more than 200 bone specimens, looking at how muscles and soft tissue attach to forelimbs, hind limbs, hip bones and vertebrae.

The results suggest the front limbs of the ceratopsids and the stegosaurs had elbows that were bent and held slightly out from the sides of the body (as though it was half-way through a press up). In comparison the hadrosaurs held their forelimbs quite close together.

Until now, scientists have just used the fossil skeletons to reconstruct what a dinosaur looked like. However, the team says the skeleton alone isn't a good predictor of how the animal stood, and it is crucial to look at the soft tissue as well. This also has implications for scientists who study behaviour and biology in other extinct animals.

'What this work shows is that before we can make any sweeping statements about the biology of dinosaurs, or any other , we have to try hard to understand the other, missing pieces of their anatomy. We can't just rely on their bones,' says Barrett.

Muscle reconstruction reveals how dinosaurs stood
Stance reconstruction and predicted trackways in (a-d) stegosaurs and ceratopsids, (e-h) ankylosaurs and (i-l) hadrosaurs. A, e and i are views of the forelimbs from the front. B, f and j are the hind legs viewed from the front. And c, g and k are side views. D, h and l are predicted trackways.

Reconstructing muscles

As such as muscles rarely fossilise, scientists use data from the dinosaurs' closest living relatives, birds and crocodiles.

'If a is present in birds, and it is also present in crocodiles, then we can be quite sure it was also present in the dinosaurs,' says Maidment. 'By looking at all of the limb muscles in crocodiles and birds through dissection, we can build up a picture of the limb muscles in the dinosaurs.'

Comparing dinosaurs

The ancestors of ceratopsids, stegosaurs and hadrosaurs were bipedal, meaning they walked on 2 legs. However, these 3 distinct but closely related dinosaur groups evolved independently, to become quadrupedal, walking on 4 legs. Even though they evolved separately, their skeletal anatomy was very similar.

Different muscles

Although their skeletons were very similar, the team found that the muscles were different, showing the ornithischian dinosaurs had more diverse methods of locomotion than previously thought.

"We were surprised to find just how different the courses of these muscles were in the different quadrupedal dinosaur groups, despite the overall similarities in the anatomy of their leg, shoulder and hip bones," says Barrett.

"Our work shows that the shape of the bones alone does not tell the full story, and that it is really important to reconstruct the soft tissues as well to work out how these dinosaurs stood," says Maidment.

Hadrosaur fossil tracks

The team’s reconstructions show that the hadrosaurs held their forelimbs quite close together and placed one foot in front of the other along a midline as they walked. Fossilised hadrosaur tracks seem to show the same thing.

Future research

Now scientists have a clearer picture of how these dinosaurs stood, the next step is to investigate how they actually moved. "We've already begun doing this and are producing 3D computational models of the limbs to look at how the muscles worked as the animals moved," concludes Maidment.

Explore further: Egypt archaeologists find ancient writer's tomb

Related Stories

Archaeopteryx and the dinosaur-bird family tree

Sep 15, 2011

The magpie-sized Archaeopteryx had bird and dinosaur features and helped show that birds evolved from dinosaurs. However, recent research in the journal Nature questions its position in the dinosaur-bird family ...

Trotting with emus, walk with dinosaurs

Oct 25, 2006

Scientists are watching emus to learn more about dinosaurs that once trotted along a long-lost U.S. coastline during the Middle Jurassic period.

Recommended for you

Egypt archaeologists find ancient writer's tomb

6 hours ago

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Crowd-sourcing Britain's Bronze Age

Apr 17, 2014

A new joint project by the British Museum and the UCL Institute of Archaeology is seeking online contributions from members of the public to enhance a major British Bronze Age archive and artefact collection.

Roman dig 'transforms understanding' of ancient port

Apr 17, 2014

(Phys.org) —Researchers from the universities of Cambridge and Southampton have discovered a new section of the boundary wall of the ancient Roman port of Ostia, proving the city was much larger than previously ...

User comments : 0

More news stories

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.