"The New York Times"
August 30, 2001

A Duck's Bill + an Ostrich's Legs = a Dinosaur

By JOHN NOBLE WILFORD

If its bill looks like a duck's and it may eat like a duck, is it a
duck? No, in this case it is a dinosaur with a long neck and legs
like an ostrich that lived more than 75 million years ago.

 Paleontologists have found rare soft tissue of such dinosaurs in
Canada and the Gobi desert of Mongolia. The animal from the Gobi
had a comblike plate in its jaw, something that has never been seen
before in a dinosaur and is strikingly similar to the
filter-feeding structure in a duck's bill.

 Both skulls also had traces of the beaks. They appeared to be made
of keratin, the material in bird beaks and human hair and
fingernails. Such a substance is seldom preserved in fossils.

 The surprising findings, reported today in the journal Nature,
suggested that fast-running dinosaurs known as ornithomimids, which
means "bird mimics," might have eaten by straining invertebrates
like tiny shrimp and other food particles from water and sediment.
This type of behavior has never been detected in a dinosaur, and
certainly not in ones as large as ornithomimids, some of which were
7 feet tall and 15 feet long.

 Ornithomimids belong to a group called theropods, which include
meat-eating predators like Tyrannosaurus rex and Velociraptor. The
more primitive ornithomimids had teeth, as do other theropods, but
they later evolved a toothless beak. They are not closely related
to the plant- eating dinosaurs known as duck- billed hadrosaurs.

 The Gobi specimen, Gallimimus bullatus, was excavated last year by
Dr. Peter J. Makovicky. Now an assistant curator of dinosaurs at
the Field Museum in Chicago, he was at the time a member of an
expedition of the American Museum of Natural History in New York
City and the Mongolian Academy of Sciences.

 "We are used to conceiving of theropods as dinosaurs with big
teeth adapted to hunting large prey," Dr. Makovicky said yesterday,
"but these beaked theropods adapted very differently and may have
lived on tiny invertebrates similar to brine shrimp."

 "Present-day birds are theropods that have adapted to a wide range
of habitats and foods," he added, "so it makes sense that theropods
adapted widely in the age of dinosaurs, too."

 Most paleontologists say that certain theropod dinosaurs were
direct ancestors of birds, although other scientists, particularly
ornithologists, do not accept the connection.

 The lead author of the Nature report, Dr. Mark A. Norell of the
American Museum, who was a leader of the Gobi expedition, said,
"While we can't definitely say that their feeding behavior was just
like that of ducks, it is unlikely that the delicate features of
their beaks were used for eating large animals."

 The other skeleton, Ornithomimus edmontonicus, was found in 1995
in Alberta by a team led by Dr. Philip J. Currie of the Royal
Tyrrell Museum of Paleontology in Drumheller, Alberta, who was an
author of the discovery report.
 

Oryginal:
http://www.nytimes.com/2001/08/30/science/30DINO.html?ex=1000200809&ei=1&en=1c8418f5b270143a

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