New research published by the Royal Tyrrell Museum on Thursday has sunk previous claims that a swimming dinosaur once paddled the rivers of the Earth.
The paper, published in scientific journal PeerJ, uses computer modelling to conclude the Spinosaurus was not adapted to swim as previously thought.
Research published in 2014 by Nizar Ibrahim and others in the journal Science proposed the dinosaur was partly aquatic, meaning it could both swim and walk on land, a first for any dinosaur.
But using different techniques that relied on physics-based testing methods, the Royal Tyrrell Museum’s curator of dinosaurs, Donald Henderson, found that the 95-million-year-old species would not have been able to survive living in water.
Henderson created three-dimensional, digital models of Spinosaurus and other predatory dinosaurs in order to test their centres of mass buoyancy and equilibrium when immersed in water. He also tested the software using models of semi-aquatic animals such as an alligator and emperor penguin, for comparison.
His models showed the Spinosaurus would have been able to float with its head above water and breath freely, just like other dinosaurs analyzed in the study.
But unlike semi-aquatic animals like alligators, which can easily self-right themselves when tipped to the side in water, the Spinosaurus rolled over onto its side when tipped slightly. The finding implied that the dinosaur species would have easily tipped over in water, forcing it to rely on its limbs to constantly maintain an upright position.
Its centre of mass was also found to be close to its hips, between its hind legs, as opposed to the centre of the torso, which had been proposed by Ibrahim’s 2014 research.
Henderson’s model found the Spinosaurus to be unsinkable underwater, something that would have severely limited its ability to hunt aquatic prey. This differentiates it from traits commonly demonstrated by living aquatic birds, reptiles and mammals, which can submerse themselves to pursue prey underwater.
“The combination of mass close to the hips, an inability to sink underwater, and a tendency to roll onto its side unless constantly resisted by limb use, suggest that Spinosaurus was not specialized for a semi-aquatic mode of life,” the researchers stated.