Scientists working in Antarctica have found fossils of what appear to be two previously unknown species of dinosaurs - a six-foot meat-eater, and one of the earliest plant-eaters ever.
The discoveries add to the small, but growing list of dinosaurs unearthed in Antarctica since 1986. Scientists said the animals adapted and thrived in a climate more akin to the Pacific Northwest than to Antarctica today.
"It was more lush," said biologist Judd Case of Saint Mary's College of California, a co-leader of one of the teams that reported their finds in Washington yesterday. "You [would have seen] snow or ice back on the hilltops, but lots of trees. ... Cool, but not cold."
Two teams funded by the National Science Foundation made their discoveries within days of each other in December, during the brief Antarctic summer.
The fossils were separated by 2,000 miles and 120 million years. The primitive plant-eater grazed about 190 million years ago, early in the Jurassic period. The carnivore hunted at the end of the Cretaceous period, just 70 million years ago.
The scientists were jubilant about their good luck. "You don't immediately want to believe it, just in case," said paleontologist William Hammer, of Augustana College in Rock Island, Ill., who led the second team. But when it sinks in, he said, "it's close to pandemonium."
Paleontologists have been finding dinosaur fossils in the Antarctic since 1986, when an Argentine team found evidence of an armored plant-eater called an ankylosaur that lived near the end of the age of dinosaurs.
The frozen continent was not always so frozen. Geologists say all the continents have been drifting around the planet for eons atop the Earth's molten mantle. Long before the dinosaurs evolved, the block that became Antarctica was actually at the Earth's equator.
It later drifted southward, reaching the polar region about 100 million years ago. But it remained connected to South America and Australia by a land bridge, and its climate was milder than it is today.
Geologist Jim Martin of the South Dakota School of Mines and Technology, said he and Case and their team sailed last fall toward a remnant of that land bridge, the Antarctic Peninsula, which stretches toward Chile.
They sought evidence that primitive marsupials migrated from the Americas - where they originated - across Antarctica to Australia.
When sea ice blocked access to Vega Island, the scientists landed on nearby James Ross Island. "We were not expecting to find any terrestrial dinosaurs," Martin said. The rocks on the island held fossils of marine invertebrates, laid down well offshore about 70 million years ago.
But near a place called Dagger Peak, Case began to find bones and teeth of a terrestrial dinosaur that must have died at the shore and floated away.
An upper jaw with curved, bladed teeth, and lower-leg and foot bones adapted for running added up to a kind of theropod - a meat-eater perhaps 6 feet tall that weighted 300 pounds.
It was only the second carnivorous dinosaur found in Antarctica. It was smaller than a tyrannosaur, Case said, but close to the size of the velociraptors portrayed in the movie Jurassic Park. "Not many dinosaurs ever were that size, which is one of the things that makes our dinosaur quite unique," he said.
And like other Antarctic dinosaurs, the creature's bones looked like those of relatives that lived elsewhere much earlier. For some reason, Antarctic dinosaurs retained their ancestors' primitive traits. "Antarctica still holds some surprises for us," Case said.
Two thousand miles farther south, in the Trans-Antarctic Mountains, Hammer and his team landed by helicopter 13,000 feet up the side of Mount Kirkpatrick, where in 1991 they discovered remains of the first Antarctic meat-eater - cryolophosaurus ( "frozen crested lizard").
This time, a mountaineer with the team found what proved to be a fossilized pelvic bone about three feet across. Hammer's team concluded that it belonged to a primitive sauropod that lived 190 million years ago - a long-necked, long-tailed plant-eater perhaps 30 feet long.
"For a sauropod that's kind of wimpy," Hammer said. "The big ones were 80 to 100 feet long."
The bones were loaded onto a ship before they could be conclusively identified, but the find is likely a species new to science. "We do know it is the largest dinosaur that's ever been found in Antarctica," Hammer said. Better still, "this could be one of the oldest sauropods in the world."