New species of dinosaur answers old questions

GAINESVILLE, Fla. — In the middle of the Sahara Desert, the carnivorous unicorn’s bones waited for a name.

Millions of years later, they got one.

Spinosaurus mirabilis, or the “astonishing spined lizard,” is the first new Spinosaurus species to be unearthed since the genus was named in 1915. It joins its relative, Spinosaurus aegyptiacus, and boasts a crest on its head whose size — about 20 inches — outstrips that of any non-avian dinosaur. To date, it is the only other species of Spinosaurus that has been discovered.

The paper is published in Science on Feb. 19.

Though finding a new dinosaur is cause for celebration, the specimen’s fossil area allows researchers to settle a long-standing academic debate about where Spinosaurus spent its time.

“Previously, some research suggested that the long spines along its tail were to help it swim, and that it was an aquatic hunter,” said Stephanie Baumgart, Ph.D., a study author and postdoctoral researcher in the Department of Physiological Sciences at the UF College of Veterinary Medicine.

But its bone density and relatively underpowered tail would not be enough to easily propel the animal through water, she said. The slender tail spines were more likely for display, and now the new bones’ location tells researchers Spinosaurus lived around water, but not in it.

Baumgart was part of an international team of researchers led by paleontologist Paul Sereno, Ph.D., at the University of Chicago. For three months, they ventured into the Sahara, excavating literal tons of fossils at multiple sites.

The inland desert location where the Spinosaurus bones were found — called Jenguebi, a region in the middle of Niger in West Africa — was previously unexcavated. Nigerien Abdul Nasser knew of bones in this area and, on his motorbike, guided a squad of Toyota Hiluxes filled with the eager scientists across the sand, with his traditional Tuareg sword slung across his back.

For the uninitiated, expeditions like this are a sequence of sandy days filled with 100-plus degree heat. The work requires the researchers to find a sweet spot between technical precision and physical endurance. Tools range from brushes the size of toothbrushes to brooms; from electric jack hammers to dental picks. At night, they cook under red headlamps. Anything else results in a thick fog of moths and other winged visitors, followed by a wave of opportunistic praying mantises. After dinner, they fall asleep under a sky free of light pollution: pitch black and peppered with shooting stars.

Discovering Spinosaurus here, about 500 to 1000 kilometers from a marine coastline, is at odds with the reality of currently living and extinct large aquatic animals. Both whales and plesiosaurs gave up a life on land, fully adapting to life in the water — flippers and all, Baumgart explained. Spinosaurus, it seems, preferred to flirt with the edges.

This new specimen of a new species was found in an inland basin environment, nestled near fossils of long-necked dinosaurs and geological clues that indicated a river system since dried up. Because the known pieces of S. mirabilis are similar in shape to S. aegyptiacus, its relative, this discovery at an inland location provides further evidence against the “aquatic hypothesis” of Spinosaurus as an open water swimmer and diver.

Instead, it likely made its living as an ambush specialist, going after fish and other prey from shallow waters.

“Adding this new information to the pre-existing information we had, it’s much more likely that it was similar to a heron — fishing from the shore or shallows, walking around and plucking food,” Baumgart said.

The “sail-backed, fish-eating giant” has long lounged in the limelight for a few reasons: Its size, which is roughly the same as that of Tyrannosaurus rex and virtually unheard of for semiaquatic predators of that period, and the way it hunted fish. Unearthing this most recent specimen points to different phases of how Spinosaurus and its relatives evolved, accounting for some of the anatomical differences in bones found thus far.

“This expands our understanding of what these dinosaurswere doing during the Cretaceous Period and how they looked,” Baumgart said.