Last year (2014) a new species of sauropod dinosaur was discovered in Patagonia and declared to be one of the largest ever found. Named Dreadnoughtus schrani to reflect its enormous proportions it was estimated to have been around 26m long. The particularly exciting thing about this specimen was that many of its long bones were intact, allowing the palaeontologists who discovered it to calculate its weight at around 60 tonnes (see How to Weigh a Dinosaur). Now a new study has cast doubt on this colossal weight.
The new research was carried out by the University of Liverpool, in collaboration with their colleagues at the University of Manchester and Imperial College, London. They applied a new method for measuring the weight of dinosaur based on its remains which aimed to estimate the animals ‘skin volume’. This technique, which has been applied to other sauropods previously, begins by constructing a computer model of the specimen based on its fossil remains. This model can then be manipulated to calculate the amount of skin needed to cover the bones, and once this has been done the skin can be expanded outwards to mimic the fat and muscle underneath as well. From the final result it is possible to calculate an overall weight for the specimen. In order to work out how to apply the skin and muscles living animals were modelled first and weighed to give some idea of the techniques accuracy.
This new method severely reduced the estimated weight of Dreadnoughtus, dropping it from a staggering 60 tonnes down to a more petite 30-40 tonnes. That is still a truly impressive animal but one that is perhaps a little more plausible given the structural limits of bone and muscle. However, it should be remembered that there is good evidence that this particular specimen of Dreadnoughtus was still growing at the time of its death and so hadn’t yet achieved its full adult weight.
Reference: Bates, K.T., et al. 2015. Downsizing a giant: re-evaluating Dreadnoughtus body mass. Biology Letters. DOI: 10.1098/rsbl.2015.0215
Featured Image: Artist’s rendering of Dreadnoughtus schrani (Illustration: Jennifer Hall )