It turns out that dinosaurs were beasts of the sea as well as the land. Palaeontologists have discovered that the Spinosaurus – possibly the largest carnivorous dinosaur ever – was adapted for moving, breathing and hunting in aquatic environments. This makes it the first known swimming dinosaur. Plesiosaurs and mosasaurs could swim, but these belonged to a different order of animals.
Researchers already knew that dinosaurs spent time around rivers and lakes, and footprints spotted on riverbeds suggested that some of them could swim, or at least splash around in the water. However, palaeontologists had never found conclusive evidence of a dinosaur that was semiaquatic, comfortable on both land and in the water, as seen in animals such as crocodiles and otters.
Now, Spinosaurus changes all that. Palaeontologists from Morocco, Italy and the US analysed recently unearthed Spinosaurus aegyptiacus fossils from the Kem Kem beds in eastern Morocco. They combined these with other remains, records and images from around the world to create a computer model and life-size 3D replica of the skeleton. Their model suggests that the dinosaur was more than 49 feet (15m) long – 9ft (2.7m) longer than the world’s largest known Tyrannosaurus rex.
“What surprised us even more than the dinosaur’s size were its unusual proportions. We see limb proportions like this in early whales, not predatory dinosaurs,” says Prof Paul Sereno from the University of Chicago.
The Spinosaurus had a number of anatomical features that were tailor-made for aquatic living. Its short hind legs and muscular thighs coupled with long flat feet and claws would have made it an excellent swimmer. It also had small nostrils located far back on its head to help it to breathe when swimming, and giant, conical-shaped teeth that were perfectly located for catching fish.
“Working on this animal was like studying an alien from outer space,” says Prof Samir Zouhri from the Université Hassan II Casablanca in Morocco. “It’s unlike any other dinosaur I have ever seen.”