Fossil
discovery proves massive African dinosaur Spinosaurus was actually a
semi-aquatic 'river monster'
Newly discovered bones from the huge African predator Spinosaurus prove it could swim, scientists say, and that the existence of this "river monster" shows some non-bird dinosaurs invaded the aquatic realm.
Scientists this week announced the discovery of fossil bones from the tail of Spinosaurus ("spine lizard"), found in south-east Morocco, which they said provided a deeper understanding of the appearance, lifestyle and capabilities of the longest meat-eating dinosaur on record.
"Spinosaurus had a highly specialised tail — a propulsive structure that would have allowed this river monster to actively pursue prey in the water column," University of Detroit Mercy palaeontologist and anatomist Nizar Ibrahim, lead author of the study published in the journal Nature, said.
Spinosaurus, which lived 95 million years ago during the Cretaceous Period, was a highly unusual dinosaur and not just because of its staggering dimensions of up to 15 meters long and more than 6,000 kilograms.
The anatomy of Spinosaurus had remained mysterious for decades after crucial fossils were destroyed during World War II, until the 2008 discovery of the Morocco skeleton. Extraction of these additional tail bones has been ongoing since 2015.
Its tail was flexible, with a large surface area thanks to a series of tall neural spines — different from the stiff and tapering tails of other carnivorous dinosaurs like Tyrannosaurus rex — indicating Spinosaurus and its close relatives engaged in tail-propelled locomotion unlike any other dinosaurs.
Laboratory experiments in which a plastic model of the Spinosaurus tail was attached to a robotic swimming device showed that the tail could move laterally to create thrust and power the animal through water like a crocodile, according to Harvard University fish biologist and biomechanist George Lauder, a study co-author.
This indicates Spinosaurus terrorised rivers and river banks as a semi-aquatic animal, not merely wading into the water waiting for fish to swim by. It may have eaten huge fish, including sharks.
"This discovery overturns decades-old ideas that non-bird dinosaurs were restricted to terrestrial environments," Harvard University vertebrate palaeontologist and biomechanist Stephanie Pierce, another study co-author, said.
"So, yes, we believe that this discovery does indeed revolutionise our understanding of dinosaur biology."
Spinosaurus still was able to move on land and lay eggs there, perhaps walking on four legs rather than two like other meat-eating dinosaurs.
"But it had so many adaptations to an aquatic existence — nostrils high on the skull and further back from the tip, flat-bottomed toe bones and claws, dense and thickened bone for buoyancy control, and this newly discovered tail form — that it would have been at least as aquatic as Nile Crocodiles," University of Portsmouth palaeontologist and study co-author David Martill said.
Ms Pierce said it "just might topple T-rex as the most famous and exciting meat-eating dinosaur".
Scientists this week announced the discovery of fossil bones from the tail of Spinosaurus ("spine lizard"), found in south-east Morocco, which they said provided a deeper understanding of the appearance, lifestyle and capabilities of the longest meat-eating dinosaur on record.
"Spinosaurus had a highly specialised tail — a propulsive structure that would have allowed this river monster to actively pursue prey in the water column," University of Detroit Mercy palaeontologist and anatomist Nizar Ibrahim, lead author of the study published in the journal Nature, said.
Spinosaurus, which lived 95 million years ago during the Cretaceous Period, was a highly unusual dinosaur and not just because of its staggering dimensions of up to 15 meters long and more than 6,000 kilograms.
The anatomy of Spinosaurus had remained mysterious for decades after crucial fossils were destroyed during World War II, until the 2008 discovery of the Morocco skeleton. Extraction of these additional tail bones has been ongoing since 2015.
Its tail was flexible, with a large surface area thanks to a series of tall neural spines — different from the stiff and tapering tails of other carnivorous dinosaurs like Tyrannosaurus rex — indicating Spinosaurus and its close relatives engaged in tail-propelled locomotion unlike any other dinosaurs.
Laboratory experiments in which a plastic model of the Spinosaurus tail was attached to a robotic swimming device showed that the tail could move laterally to create thrust and power the animal through water like a crocodile, according to Harvard University fish biologist and biomechanist George Lauder, a study co-author.
This indicates Spinosaurus terrorised rivers and river banks as a semi-aquatic animal, not merely wading into the water waiting for fish to swim by. It may have eaten huge fish, including sharks.
"This discovery overturns decades-old ideas that non-bird dinosaurs were restricted to terrestrial environments," Harvard University vertebrate palaeontologist and biomechanist Stephanie Pierce, another study co-author, said.
"So, yes, we believe that this discovery does indeed revolutionise our understanding of dinosaur biology."
Spinosaurus still was able to move on land and lay eggs there, perhaps walking on four legs rather than two like other meat-eating dinosaurs.
"But it had so many adaptations to an aquatic existence — nostrils high on the skull and further back from the tip, flat-bottomed toe bones and claws, dense and thickened bone for buoyancy control, and this newly discovered tail form — that it would have been at least as aquatic as Nile Crocodiles," University of Portsmouth palaeontologist and study co-author David Martill said.
Ms Pierce said it "just might topple T-rex as the most famous and exciting meat-eating dinosaur".
