Dino jaws: Stegosaurs bite strength revealed

The first detailed study of a Stegosaurus skull shows that it had a stronger bite than its small peg-shaped teeth suggested. The Natural History Museum’sStegosaurus specimen, ‘Sophie’, has been compared with two plant-eating dinosaurs with similar skulls:Plateosaurus and Erlikosaurus.

All three had a large low snout and a scissor-like jaw action that moved up and down. Using computer modelling a team of scientists from Bristol, London, Manchester and Birmingham, including Charlotte Brassey from The University of Manchester, has shown these dinosaurs had different biting abilities.

As Prof Paul Barrett, dinosaur researcher at the Natural History Museum explains: “Far from being feeble, as usually thought, Stegosaurus actually had a bite force within the range of living herbivorous mammals, such as sheep and cows.”

The finding means that scientists need to reconsider how Stegosaurus fitted into its ecological niche. For example it may have had a role in spreading the seeds of woody evergreen cycads.

Stegosaurus lived around 150 million years ago and needed to eat a lot of plants to sustain its large size. As grasses did not exist then, it would have fed on plants such as ferns and horsetails.

As Barrett, leader of the research team, comments: “Our key finding really surprised us: we expected that many of these dinosaur herbivores would have skulls that worked in broadly similar ways. Instead we found that even though the skulls were fairly similar to each other in overall shape, the way they worked during biting was substantially different in each case.”

Lead author Dr Stephan Lautenschlager, a post-doctoral researcher at the University of Bristol’s School of Earth Sciences, employed digital models and computer simulations to analyse the dinosaurs’ bites, using data from 3D scans of the skulls and lower jaws. He used engineering software to give the skulls the material properties that would match as closely as possible to the real thing, for example, using data on crocodile teeth to model those of the dinosaurs.

By attaching muscles to the models, he was able to examine the forces that the jaws could produce and the subsequent stresses on the skulls.

As computer power increases and software becomes more available, Lautenschlager thinks that we will see more modelling used in dinosaur research: “Using computer modelling techniques, we were able to reconstruct muscle and bite forces very accurately for the different dinosaurs in our study. As a result, these methods give us new and detailed insights into dinosaur biology – something that would not have been possible several years ago.”

Further images are available at  https://nhm.box.com/s/fnaf66vdo8bbrekfilwu3b7di8q327zf Please note: images are for single use only to illustrate this press release and are not to be archived.All images © Stephan Lautenschlager

Original PublicationLautenschlager, S., Brassey, C. A., Button, D. J., Barrett, P. M. Decoupled form and function in disparate herbivorous dinosaur clades. Sci. Rep. 6, 26495; doi:10.1038/srep26495 (2016)

Downsizing a giant

Collaboration between four UK universities has found that the world’s largest dinosaur isn’t quite as big as previously thought.

Credit: Biology Papers.

Faculty scientists from The University of Manchester teamed up with scientists from the University of Liverpool, Liverpool John Moores and Imperial College London to help create a computer reconstruction of a dinosaur called Dreadnoughtus. They used this model to help predict the overall mass of the now extinct animal.

Dreadnoughtus, a herbivore with a long neck and tail, was thought to weigh around 60 tonnes but this new model puts the dinosaur’s weight at a more moderate 38 tonnes.

The original estimate of 60 tonnes came from a calculation that was based on the circumference of one of the dinosaur’s fossilised remains and then comparing that to animals that are alive today and their weights. However, the team used a different approach. They fitted simple shapes to a digital model of the Dreadnoughtus’ skeleton and calculated the volume. This volume was then converted into a body mass, using data collected from similar modern animals.

Dr Charlotte Brassey who headed up the Faculty’s involvement explains the results:

“The model we have used here shows that for Dreadnoughtus to have reached the originally estimated size it would have either needed a much higher body density, or much more soft tissue than you find in living four-legged animals.”

She adds:

“While Dreadnoughtus was clearly a huge animal, we don’t think it would have grown to quite as big as the 60 tons originally claimed.  Estimating the size of an animal from its bones necessarily means you have to theorise, but we think our figure fits much better with what we currently understand about the size and shape of modern land animals.”

The paper, ‘Downsizing a giant: re-evaluating Dreadnoughtus body mass’, has been published in the Royal Society journal Biology Letters.

Digital reconstruction of giant dinosaur steps

dinosaurFaculty scientists have helped digitally reconstruct one of the world’s largest dinosaurs, allowing it to take its first steps in over 94 million years. The team, working alongside scientists in Argentina, began by scanning a 40-metre skeleton of the Cretaceous Argentinosaurus dinosaur. They then used advanced computer modelling techniques to recreate its walking and running movements and test its locomotion ability for the very first time.

The study provides the first ever ‘virtual’ trackway of the dinosaur. Dr Bill Sellers, lead researcher on the project, said:

“If you want to work out how dinosaurs walked, the best approach is computer simulation. This is the only way of bringing together every strand of information we have on this dinosaur, so we can reconstruct how it once moved. These animals are not like anything alive today, so we can’t just copy a modern animal. Our machine learning system works purely from the information we have on the dinosaur and predicts the best possible movement patterns.”

Argentinosaurus weighed 80 tonnes and the simulation shows that it would have moved at around 5 mph – barely above a human’s walking speed. The research does more than simply tell us about the movement of this particular dinosaur, though. It also increases understanding of musculoskeletal systems and will help the development of robots. Dr Sellers added:

“All vertebrates share the same basic muscles, bones and joints. To understand how these function we can compare how they’re used in different animals. The most interesting are often those at extremes. Argentinosaurus is the biggest animal that ever walked on the surface of the earth and understanding how it did this will tell us a lot about the maximum performance of the vertebrate musculoskeletal system. We need to know more about this to help understand how it functions in humans. Similarly, if we want to build better legged robots then we need to know more about the mechanics of legs in a whole range of animals. Nothing has bigger, more powerful legs than Argentinosaurus.”