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A New Dino Duo

As a paleontologist, James Kirkland has examined thousands of different dinosaur bones. But even he wasn't prepared for what he saw when he was called to investigate some new fossils found near Salt Lake City, Utah. A fossil bed there held the bones of two never-before-seen species of ankylosaur. The discovery, announced last week, is changing scientists' ideas about the history of dinosaurs in America.

Heavy Weapons
Both of the newly discovered creatures belong to a group of plant-eating dinosaurs called ankylosaur, which means "fused lizards." The name comes from the heavy armor-like plates attached or fused to their heads. Some grew more than 30 feet long.

"These two dinosaurs were very similar animals in many respects," says Kirkland. One is an ankylosaurid. Ankylosaurids had big armored plates around their head and a long tail with a heavy club at the end. They would swing the club-tail to fight bigger animals, like the Tyrannosaurus rex.

The other new species, the nodosaurid, was also well armed. It had spikes on its shoulders. "It used to ram larger creatures," says Kirkland. "These dinosaurs were built like tanks."

Most ankylosaurs lived 148 million to 64 million years ago, during the last dinosaur era, known as the Late Cretaceous period. They lived in Asia and apparently crossed over to America on a land bridge that once connected Asia to what is now Alaska. "Ankylosauria was in a real hurry to get over here from Asia," says Kirkland. "They were some of the first to get here."

By studying volcanic ash found near the site, scientists have determined that the ankylosaurid bones were 25 million years older than any other known American ankylosaur. This means that the land bridge must have existed earlier than scientists had believed. Paleontologist Kenneth Carpenter says these findings push the date that the land bridge existed back from 90 million years ago to 110 million years ago.

The skull and armor of the ankylosaurid and the shoulder blade of the nodosaurid are being studied by experts at the College of Eastern Utah Prehistoric Museum. Already they have learned that the head armor of the ankylosaurid is not a bunch of plates attached to its head but an outgrowth of its skull bones. They are eager to discover more about these armed warriors of a lost world.

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