Palaeontologists from multiple universities in the UK have revealed through a new research that the most complete giant sauropod dinosaur, Dreadnoughtus, which was discovered in Patagonia, South America in 2014, was not as large as previously thought.
The huge fossil of the giant sauropod dinosaur had almost all of the major bones intact, which enabled scientists to confidently estimate its overall size – measuring in at 26 metres long. Researchers at the time believed that the animal was close to maturity but not fully grown when it died, and may have grown to be even larger. The long-necked, plant-eating dinosaur was the biggest to ever walk the earth.
Back when it was originally discovered, scientists used a scaling equation that predicts body mass based on the size of thigh and arm bones to estimate the mass of Dreadnoughtus. According to estimates, the mass of the giant dinosaur was pegged as colossal 60 tonnes.
Scientists from Universities of Liverpool, Manchester, Liverpool John Moores University, and Imperial College, re-evaluated the estimate after it became clear that other sauropod dinosaurs, only marginally smaller than the giant, weighed considerably less than 60 tonnes.
Using a three-dimensional skeletal modelling technique to examine body mass more directly, the researchers mathematically reconstructed a ‘skin’ volume around bones of Dreadnoughtus on a computer and then expanding that skin outline to account for muscle, fat and other tissues. The researchers based the size of expanded skin outline on similar data from living animals. By exploring a range of expansions the team could more accurately predict how heavy Dreadnoughtus could realistically have been.
Based on their modelling technique, researchers estimate the mass of the Dreadnoughtus between 30 and 40 tonnes, considerably less than originally thought.
Dr Karl Bates, from the University’s Institute of Ageing and Chronic Disease, explained that the original method used to calculate the mass of the animal is a common one and has been used successfully on many specimens. The highest estimates produced for this particular giant, however, didn’t quite match up.
Bates added that based on digital modelling and a dataset that took in species, alive and dead, they were able to see that the creature couldn’t be as large as originally estimated.”
“Our analysis suggests that only the lower estimates produced by previous methods are plausible. Estimates of 60 tonnes and above do not fit with our current understanding of the mass characteristics of living land animals”, Bates added.
It is unclear how accurate previous predictions on the scale of these creatures have been, but future studies of living animals and developments in modelling techniques could help build a more fulsome picture of the size and lifestyles of the dinosaurs.
The research is published in the Royal Society journal Biology Letters.