Dinosaur 'Missing Link' Found in UtahPhoto: Utah State Paleontologist James Kirkland displays a full-size cast of the
newly discovered dinosaur falcarius utahensis. (Courtesy Gaston Design, Inc.) May 5, 2005; Page A08
By Guy Gugliotta
Washington Post Staff Writer
Digging in the badlands of east central Utah on a tip from a repentant poacher, researchers have unearthed the fossil remains of a dinosaur "missing link," a primitive plant-eater that had recently evolved from the carnivorous raptors, which also produced modern birds.
"They probably used the claws for self-defense," said Utah state paleontologist James I. Kirkland. "Or maybe they were herding animals who just hung out together and hoped the predators would eat someone else."
The discovery of Falcarius utahensis, or "sickle-maker from Utah," so named because of the claws, supports earlier research linking plant-eating dinosaurs known as therizinosaurs to raptors. It also opens the possibility that therizinosaurs may have originated in North America rather than Asia, as previous evidence suggested.
The findings are being reported today in the journal Nature.
"It's an extremely significant find," said Matthew Lamanna, a Carnegie Museum of Natural History paleontologist who was not a member of the Utah team. "Before this discovery, the oldest known animal recognized as a therizinosaur came from China, and this one is just as old and seems to be more primitive anatomically. It appears to be the final piece of the puzzle."
Kirkland said in a telephone interview that he first became aware of Falcarius utahensis in 1999, when colleagues showed him a box of bone fragments they had bought at a fossil show in Tucson. The bones were said to have come from private land, Kirkland said. It is illegal to excavate fossils on public land without a permit.
Kirkland said he tried "over a number of years" to ascertain the location of the site and finally got directions from an acquaintance of the excavator. When Kirkland still could not find it, Lawrence Walker, the poacher, anxious to see his discovery properly recognized, admitted his role and guided him in.
In rugged country about 140 miles southeast of Salt Lake City, Kirkland found the jumbled remains of "hundreds, perhaps thousands" of falcarius embedded in a two-acre stretch of pebbly, 120 million-year-old mudstone on a mesa top once washed by the waters of an ancient spring.
"Ninety-nine percent of the bones were the same animal," Kirkland said, but the site offered few clues about how so many falcarius died suddenly in the same place. "Personally, I favor poison," he said, either from botulism from dead animals in the water, or "some kind of microbial bloom." The spring might also have belched a cloud of carbon dioxide, methane or sulfur dioxide, asphyxiating the herd.
"It was pretty exciting," Kirkland recalled. He turned to Walker, warning him "that I wasn't going to call the FBI, but if they call me up, I'll have to tell them." Sure enough, federal agents approached Kirkland when he asked for a permit.
Walker eventually pleaded guilty to theft of government property, paid a $15,000 fine and spent five months in prison.
Kirkland's team began excavating in 2001. Falcarius measured about 12 feet from the tip of its long neck to the end of its long tail. Like raptors, it stood upright and had the powerful hind legs of a running, carnivorous predator. But its teeth were tiny and leaf-shaped, designed for shredding forage, and it had an atypically wide pelvis capable of supporting the large gut needed to digest vegetation. And the back legs were slightly bowed and thickened, suggesting a more sedentary lifestyle than the predatory raptors.
"It looks like a long-necked raptor," said team member Scott Sampson, curator of vertebrate paleontology at the Utah Museum of Natural History at the University of Utah. "We're not saying it's a vegan. Maybe an omnivore."
The key features were the arms and claws, more powerful than those of many raptors, but not big or blocky enough to support a large, plant-eating quadruped.
"The claws look like blades on a scythe," Lamanna said. "They could swing their arms with quite a bit of force."
Link to Article Source
|
|
