WASHINGTON - An enormous predatory dinosaur with a skull like a crocodile’s and foot-long (30-centimeter-long) thumb claws was discovered in the Sahara by an international team, led by Paul Sereno of the University of Chicago.
Measuring 36 feet (11 meters) in length and 12 feet (4 meters) high at the hip, the specimen is the most complete known of a peculiar group of fish-eating predators called spinosaurs, animals that grew to the size of Tyrannosaurus rex. Sereno and colleagues name the new species Suchomimus tenerensis, meaning “crocodile mimic from Ténéré,” a remote and forbidding, dune-covered region of the Sahara in the Republic of Niger in West Africa.
Painting by Michael Skrepnick
"A dinosaur trying hard to be a crocodile,” is the way paleontologist Paul Sereno describes the 36-foot (11-meter) spinosaur he and his team discovered in a remote part of the Sahara. The animal’s long skull resembles a crocodile’s, and so do its hooklike teeth, which were adapted for eating fish. The animal had huge, muscular forearms, used for grabbing things as it walked on its hind limbs. A sail—probably used for display—ran down its spine.
Sereno, a paleontologist, and a 15-member expedition spent more than two months in fall 1997 scouring the desert in temperatures that climbed to 120°F (49°C). They unearthed 25 tons of bone and rock that included the remains of Suchomimus.
Team member David Varricchio spotted the huge, sickle-shaped thumb claw. “It was lying on the surface of the desert, completely exposed by wind and sand, and would have been visible like that for centuries to anyone who walked by,” Sereno said. The claw led the team to 400 pieces of the skeleton, buried just inches under the desert plain.
The discovery reveals new information about the peculiar anatomy of spinosaurs. “It was a dinosaur trying hard to be a crocodile,” Sereno said. Its four-foot-long (1.2-meter-long) skull has an extremely long and narrow snout with large teeth near its end, as in specialized fish-eating crocodiles. The jaws were studded with more than 100 conical teeth that functioned like hooks rather than slicing blades.
The foot-long (30-centimeter-long) thumb claws and powerfully built forelimbs were used to snare fish and other prey as the dinosaur waded in rivers; the thin, bony sail along its back, which reached a height of two feet (0.6 meter) over the hips, may have been brightly colored for display.
Suchomimus lived in Africa about 100 million years ago in what was then a forested region dissected by broad rivers and home to other dinosaurs, huge crocodiles, turtles, pterosaurs and many kinds of fish. It wouldn’t have been a friendly place, Sereno said. “If you weren’t grabbed by a spinosaur, you’d likely run into a 50-foot [15-meter] crocodile.”
Suchomimus was the largest and most common predator of its day, judging from the numerous bones Sereno’s team recovered. Its closest cousin is Baryonyx from Europe rather than the tall, sail-backed north African spinosaurid Spinosaurus. This far-reaching link suggests that, on at least one occasion, spinosaurs crossed the broad Tethyan seaway that separated northern and southern land masses at that time.
Spinosaur fossils were first discovered in Niger’s Ténéré Desert some 50 years ago and were collected in earnest 25 years ago by French paleontologists. The region’s fossil-rich rock provides the best opportunity to unearth clues to plants and animals that thrived in Africa 100 million years ago, as the continent was drifting into geographic isolation.
The expedition and laboratory work on the fossils was supported by the National Geographic Society, the David and Lucile Packard Foundation, the Pritzker Foundation, and the Women’s Board of the University of Chicago.