Fossil sheds new light on species
Judd Case had spent a lot of time in the Antarctic, and seen a lot of fossils.
There were the hadrosaur bones he found in 1998. And the head and feet of a previously undiscovered species of raptor – everything but the “tasty bits” – he dug up in 2004. And countless pieces of teeth and bone he and his team gathered over years of fossil hunting around the South Pole.
But when he saw a string of vertebrae in the permafrost terrain of Vega Island in 2005, he knew they’d found something special.
“We realized we had a whole skeleton,” said Case, the new dean of science, health and engineering at Eastern Washington University. “This thing had all sorts of details we hadn’t seen before.”
What Case and his colleagues unearthed was the skeleton – complete with rib cage – of a baby plesiosaur, about 70 million years old, a “unique specimen” in the world of fossils, he said. Plesiosaurs were marine reptiles with long necks, small heads and flippers. The fossil is about 5 feet long, but the creatures grew to as longas 40 feet.
Typically, even the most complete fossils don’t have cartilage remaining to keep bones and rib cages in place. In this case, however, the baby plesiosaur was found in a layer of volcanic ash that preserved some of that tissue, Case said.
Case and his colleagues will announce the discovery today at a news conference in Washington, D.C., and the fossil will be available for public viewing this week at the South Dakota School of Mines & Technology.
Case began hunting for fossils in Antarctica as a graduate student, and he became the chief scientist of his current team in 1998. The team includes Jim Martin of the School of Mines and several other scientists. It’s funded by the NSF, as well as the Argentine Antarctic Institute. Case was a researcher and dean at St. Mary’s College of California for 16 years, and came to EWU about 10 weeks ago.
Case’s work environment can be daunting. Bare sediment is rare in icy Antarctica, and digging can be slow. It’s cold – 40 degrees is balmy – and the team lives in tents on the windy tundra. Sometimes they travel to and from their camp by ship, a four-day journey over choppy seas.
Antarctica probably served as a migratory path for dinosaurs between South America and India, and Case’s career has been spent filling in the pieces of ancient life in that region.
In 1998, he found the bones of a hadrosaur – a plant-eater that spent a lot of time on two legs and filled a “cow role,” he said. The hadrosaur was a common dinosaur in North America, but the discovery in Antarctica suggested they’d migrated farther south than previously known.
Then in 2004, Case and his colleagues found a previously undiscovered species of carnivorous raptor – which the NSF described as a relative of T. rex and the velociraptors made famous in “Jurassic Park.” They’re part of a class of dinosaurs known as theropods, believed to be the ancestors of birds.
Case’s raptor was also found farther south than other raptors, suggesting that the creatures had migrated based on changes in the dispersal of flowering plants – plant eaters migrated south, followed by smaller meat-eaters, etc.
In 2005, Case and his team spent January and February back on Vega Island, looking for fossils in an area that during the dinosaur era was shallow ocean close to shore. Because the area would have been somewhat protected from predators and rocky seas, Case said he thinks it was something of a nursery for marine reptiles, and his team has found lots of bones of young creatures.
When they discovered the full plesiosaur skeleton, they dug it out, packed it in plaster to protect it and sent it back to the School of Mines in South Dakota. They’ve uncovered half of the fossil, analyzed it and made a resin replica.
One thing they discovered is that the young creature had already ingested stones – a characteristic of the species that scientists have wondered about. Case said it’s unclear whether the stones were used for a digestive purpose – like chickens – or for ballast so the sea reptiles could sink more easily. Whatever the case, the discovery of the new fossil shows that the creatures had eaten the stones from a very young age.
Case hopes to take another research trip to Antarctica in January 2008. One reason to return is to keep exploring the reasons why marsupial life became so rich and varied on Australia – land of kangaroos and koalas – compared with marsupial life elsewhere. Australia once was part of the Antarctic land mass, and Case’s team hopes to find answers in the Antarctic fossil record.
“When did that happen and what does that original ancestor look like, and was it a single ancestor or were there several?” he said.