Fattysaurus or thinnysaurus? How dinosaurs measure up with laser imaging

Feb 19, 2009

(PhysOrg.com) -- University of Manchester scientists are using laser imaging to investigate how fat - or fit - T. rex and his fellow dinosaurs were.
Karl Bates and his colleagues in the palaeontology and biomechanics research group have reconstructed the bodies of five dinosaurs, two T. rex (Stan at the Manchester Museum and the Museum of the Rockies cast MOR555), an Acrocanthosaurus atokensis, a Strutiomimum sedens and an Edmontosaurus annectens.

The team, whose findings are published in the Public Library of Science journal PLoS ONE today (19th February 2009), found that the smaller Museum of the Rockies T. rex could have weighed anywhere between 5.5 and 7 tonnes, while the larger specimen (Stan) might have weighed as much as 8 tonnes.

Acrocanthosaurus atokensis was a large predatory dinosaur that looked like T. rex but with large spines on its back and roamed the earth much earlier in the mid Cretaceous period, around 110M years ago. The team suggest Acrocanthosaurus probably weighed in at a similar mass to MOR555 and other medium sized adult T. rex at about 6 tonnes.

The Strutiomimum sedens, whose name means “ostrich mimic”, lived alongside T. rex in the late Cretaceous period and probably weighed somewhere between 0.4 - 0.6 tonnes

The reconstruction of Edmontosaurus annectens, a plant-eating hadrosaur was based on a juvenile specimen, but still weighed in at between 0.8 - 0.95 tonnes. As adults, some hadrosaurs grew as big as T. Rex, again living in the late Cretaceous period.

The team used laser scanning (LiDAR) and computer modelling methods to create a range of 3D models of the specimens, attempting to reconstruct their body sizes and shape as in life. The laser scanner images the full mounted skeleton, resulting in a detailed 3D model in which each bone retains its spatial position and articulation. This provides a high resolution skeletal framework around which the body cavity and internal organs such as stomach, lungs and air sacs can be reconstructed. This has allowed calculation of body segment masses, centres of mass and moments of inertia for each animal - all the information that is needed to analyse body movements.

Having created their ‘best-guess’ reconstruction of each animal, they then varied the volumes of body segments and respiratory organs to find the maximum plausible range of mass for the animals. Even scientists cannot be sure exactly how fat or thin animals like T. rex were in life, and the team were interested in exactly how broad the range of possible values were for body mass. They believe that the lower weight estimates are most likely to be correct as there is no good reason for the dinosaurs to weigh more than they need to as this would affect their speed, energy use and demands on the respiratory system.

The team also measured the body mass of an ostrich, as an existing subject that would show how accurate their technique was, and found the results to be correct.

They will now use the results to further investigate the locomotion of dinosaurs, specifically how they ran.

Karl said: “Our technique allows people to see and decide for themselves how fat or thin the dinosaurs might have been in life. You can see the skeleton with a belly. Anyone from a five-year-old to a Professor can see it and say, ‘I think this reconstruction is too fat or too thin’.

He added: “This study will help us in our research on how dinosaurs ran in 3-D rather than 2-D as in previous studies.

“Reconstructing more dinosaurs in such detail will allow us to examine changes in body mass and particularly centre of mass as they evolved. As we know, dinosaurs evolved into birds. As they did so, the centre of mass moved forward and different walking styles evolved. Although the dinosaurs we have reconstructed are not very close relatives of the birds, we can nevertheless see a small forwards movement in the position of the centre of mass from Acrocanthosaurus atokensis to the T. rex, which lies closer to modern birds on the evolutionary lines.”

More information: The paper ‘Estimating Mass Properties of Dinosaurs Using Laser Imaging and 3D Computer Modelling’ in PLoS ONE is available at dx.plos.org/10.1371/journal.pone.0004532

Provided by University of Manchester

Explore further: Graeco-Roman papyrus memoirs reveal ancient Egyptian treatment for hangover

Related Stories

Nepal quake: Nearly 1,400 dead, Everest shaken (Update)

9 hours ago

Tens of thousands of people were spending the night in the open under a chilly and thunderous sky after a powerful earthquake devastated Nepal on Saturday, killing nearly 1,400, collapsing modern houses and ...

Russian hackers read Obama emails, report says

9 hours ago

Emails to and from President Barack Obama were read by Russian hackers last year in a breach of the White House's unclassified computer system, The New York Times said Saturday.

Supermarkets welcome cold-comfort edge of F1 aerofoils

14 hours ago

UK-based Williams Advanced Engineering, the technology and engineering services business of the Williams Group, has collaborated with UK-based Aerofoil Energy to develop an aerodynamic device that can reduce ...

Public boarding school—the way to solve educational ills?

18 hours ago

Buffalo's chronically struggling school system is considering an idea gaining momentum in other cities: public boarding schools that put round-the-clock attention on students and away from such daunting problems as poverty, ...

Recommended for you

Deciphering the demise of Neandertals

Apr 24, 2015

Researchers from the University of Bologna, Italy, and the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, analysed two deciduous teeth from the prehistoric sites of Grotta di Fumane ...

Human ancestors had tentacles

Apr 23, 2015

The famous Vitruvian Man drawn by Leonardo da Vinci pictures the canon of human proportions. However, humans didn't become bilaterally symmetric suddenly. There are two main points of view on the last common ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.