Researchers revealed what is believed to be the first example of a true semiaquatic dinosaur, Spinosaurus aegyptiacus.
The giant Cretaceous-era predator is believed to have adapted to life in the water about 95 million years ago, the National Geographic Society reported. This is most likely the first evidence of a dinosaur that could live and hunt in an aquatic environment.
The dinosaur was about nine feet longer than the feared Tyrannosaurus rex. An international research team found the Spinosaurus developed a variety of aquatic adaptations. The team made its findings after analyzing new fossils discovered in the Moroccan Sahara and others that had been uncovered in the past.
"Working on this animal was like studying an alien from outer space; it's unlike any other dinosaur I have ever seen," said lead author Nizar Ibrahim, a 2014 National Geographic Emerging Explorer.
The researchers created a digital model of the skeleton, and bones missing from the specimen were modeled based on known elements of related dinosaurs.
"We relied upon cutting-edge technology to examine, analyze and piece together a variety of fossils. For a project of this complexity, traditional methods wouldn't have been nearly as accurate," said Simone Maganuco from the Natural History Museum in Milan, Italy.
The team used digital modeling to create an "anatomically precise, life-size 3-D replica of the Spinosaurus skeleton." The Spinosaurus was measured from head to tail, confirming the calculations that the new specimen was larger than the Tyrannosaurus.
"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," said Paul Sereno from the University of Chicago.
"In the last two decades, several finds demonstrated that certain dinosaurs gave origins to birds. Spinosaurus represents an equally bizarre evolutionary process, revealing that predatory dinosaurs adapted to a semiaquatic life and invaded river systems in Cretaceous North Africa," said Cristiano Dal Sasso, also from the Milan Natural History Museum.
Some of the dinosaur's adaptive features include: small nostrils in the middle of the skull that allowed the dinosaur to breathe when its head was partially above water; neurovascular openings at the end of the snout similar to a crocodile's that allow it to sense movement in the water; giant slanted teeth ideal for catching fish; a small pelvis with muscular legs to help with swimming; and strong, long-boned feet to use as paddles.
The findings were published in the October National Geographic magazine cover story available online Sept. 11.
