Fish-Eating Dinosaur Found in Africa.
Together with similar species found on three continents, the Niger animal shows how a group of related predatory dinosaurs underwent a profound evolutionary transformation--one that sculpted the familiar dinosaur face into a snout that would appear, from above, to be as long as a baseball bat and just as narrow.
"It's a bizarre thing. It looks like a long-snouted crocodile," says paleontologist Paul C. Sereno of the University of Chicago, who led the African expedition last December. In the Nov. 13 Science, Sereno and his colleagues describe the newfound species, which they named Suchomimus tenerensis, meaning crocodile mimic from the Tenere Desert. "It must have been a very effective form for catching fish," suggests Sereno.
Suchomimus belongs to a group of theropod dinosaurs called spinosaurids, first discovered by German paleontologists working in Egypt in 1912. The original specimen, named Spinosaurus, was destroyed during World War II, and it wasn't until 1973 that a French paleontologist unearthed jaw fragments of a similar dinosaur in Niger. Philippe Taquet of the National Museum of Natural History in Paris marveled at that dinosaur's resemblance to the gavial, a modern crocodile with a long, thin snout. He imagined such dinosaurs fishing on the shores of lakes, much like herons.
In 1983, paleontologists in southern England found the first reasonably complete spinosaurid specimen. The animal, named Baryonyx, had the characteristic long snout and also a giant curved claw.
The new find by Sereno and his colleagues reveals that spinosaurids had faces even more extreme than previously recognized. The snout of Suchomimus extends 25 percent farther than researchers had calculated for other spinosaurid specimens. The animal would have reached 11 meters in body length and had thumb. claws measuring 33 centimeters long, which in life bore a horny coating that would have extended the claw another 10 cm, says Sereno.
Angela Milner of the Natural History Museum in London says that some elements of Suchomimus are more complete than those of Baryonyx, which she named and studied. "This fills in some parts of the animal that we didn't have, and it gives us more [characteristics] to work out the relationships of these dinosaurs to other groups," she says.
Suchomimus had elongated spines on its back vertebrae, forming a low sail over its hips. This species is midway between Baryonyx, which had no such structure, and Spinosaurus, which had a tall sail, says Milner.
Hans-Dieter Sues of the Royal Ontario Museum in Toronto, who is analyzing fragments of a spinosaurid that was found in northeast Brazil, says the animals' snouts defy easy answers. "The whole skull has the most unusual shape for any dinosaur. It raises an interesting question of what these animals did for a living."
Partially digested fish remains rest inside the ribs of Baryonyx, reinforcing the theory that it consumed fish. Sues, however, doubts that the dinosaur snouts were specialized for fishing, noting that they differ in important ways from those of crocodiles. Baryonyx, he points out, had the bones of a herbivorous dinosaur in its gut alongside the fish remains.
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|Article Type:||Brief Article|
|Date:||Nov 14, 1998|
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