A team of paleontologists headed by Dr Karl Bates from the University of Liverpool has shown that a supermassive titanosaurian dinosaur called Dreadnoughtus schrani, discovered several years ago in south-western Patagonia, Argentina, was not as large as previously estimated.
Rendering of Dreadnoughtus schrani in life. Image credit: Jennifer Hall.
Dreadnoughtus schrani lived in the temperate forests of what is now the south of South America during Cretaceous, approximately 77 million years ago.
More than a hundred bones and a single tooth representing two individuals of Dreadnoughtus schrani were recovered in the period 2005-2009 from the Cerro Fortaleza Formation in Santa Cruz Province, Argentina, and later described as a new species of titanosaur by Dr Kenneth Lacovara of Drexel University and his colleagues.
To estimate the mass of the prehistoric monster, Dr Lacovara’s team used a scaling equation that predicts body mass based on the size of thigh and arm bones. This method produced a range of estimates with the average being a colossal 59.3 tons.
Now, Dr Bates and his colleagues have re-evaluated this estimate after it became clear that other sauropod dinosaurs, only marginally smaller than the giant, weighed considerably less than 60 tons.
The paleontologists used a 3D skeletal modeling technique to examine body mass more directly. This method involves mathematically reconstructing a skin volume around bones of the dinosaur on a computer and then expanding that skin outline to account for muscle, fat and other tissues.
They found that the mass of the Dreadnoughtus schrani was more likely to be between 30 and 40 tons, considerably less than originally thought.
“Our analysis suggests that only the lower estimates produced by previous methods are plausible. Estimates of 60 tons and above do not fit with our current understanding of the mass characteristics of living land animals,” said Dr Bates, who is the first author of results published in the journal Biology Letters.
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Karl T. Bates et al. 2015. Downsizing a giant: re-evaluating Dreadnoughtus body mass. Biology Letters, vol. 11, no. 6; doi: 10.1098/rsbl.2015.0215
