Arizona Discovery : Dinosaur Bones Believed to Be Oldest Ever Found

Scientists have discovered what is believed to be the oldest dinosaur skeleton in the world while digging through a rich bed of fossils in the heart of Arizona’s Petrified Forest National Park, the University of California, Berkeley, announced Wednesday.

The discovery “pushes back the history of dinosaurs quite a ways, at least 5 to 10 million years,” said Michael Greenwald of the university’s Museum of Paleontology. “It’s very exciting.”

The bones, dated at more than 225 million years old, belonged to “a totally new animal” that was believed to have been a very early forerunner of the giant brontosaurus--the largest animal that ever walked the Earth. Greenwald said the new dinosaur was much smaller, probably about the size of a small ostrich.

Teams of paleontologists from Berkeley and the University of Colorado have found at least one complete leg, several thigh bones, ribs, vertebrae and other remains, all in exceptionally good condition. The bones were preserved in the silty clay of the Painted Desert just one mile from a viewing area that is popular among the hundreds of thousands of tourists who visit the park each year.

“It’s a spectacular specimen,” Greenwald said. “Normally we find bits and pieces, but in this case we’ve got at least two individuals, because we’ve found parts of three (rear) legs. There’s a good chance we will get a fairly decent skeleton.”

Berkeley paleontologist Robert Long, the leader of the team, said Wednesday that the fossils, along with the region’s petrified plants that help document the age of the bones, provide “by far the best picture anywhere in the world” of the dawn of the dinosaur age. The Petrified Forest area is “the only place where you get complete association of plants and animals,” he said. “You can see a tremendous diversity of organisms. We can reconstruct scenes.”

The bones have been dated by “biostratigraphy,” a system that uses the well-established dates of plants and other organic materials found in nearby rocks to determine the age of other fossils.

Greenwald said the age of the new animal is “pretty absolute,” making it by far the oldest dinosaur ever found in the Northern Hemisphere. Dinosaur bone fragments found in Brazil in the late 1960s had first been described as being about the same age, but Long said British experts who have studied the South American bones now believe that their age cannot be determined with confidence.

Better Preserved

Long said the Arizona bones can be dated “with great clarity” and are far better preserved. That should yield a more complete replication of the animal, which he said will be returned to the Petrified Forest for public viewing.

The first discovery of the dinosaur bones was made late last summer by Brian Small, a graduate student from Texas Tech University who was working with Long. Examination of the site yielded numerous bones, including a complete leg, indicating that the animal died where the bones were found. Further exploration uncovered a rich layer of dozens of bones and fossils.

By the time Small made his discovery, many of the scientists had to return to their universities for the fall term, so teams of paleontologists will close in on the area later this month to excavate the site. The scientists will cut around the siltstone that has protected the bones for millions of years, then pour plaster around the clay, creating a protective package that can be taken to the Berkeley museum.

Return Planned

The scientists will return to the site on May 29 and begin preliminary excavations. The bones are scheduled to be moved June 6.

Paleontologists from around the country are expected to visit the site during that period.

“Paleontology is a small field,” Greenwald said. “We all know each other, and any time anything like this happens, there’s a lot of excitement.”

He said he and his fellow scientists expect to be “up to our hips, so to say,” in visiting colleagues.

Long, who has spent 20 years studying the ancient past of the Petrified Forest, said the new discovery gives him hope that scientists will find more insights into the origins of the giant beasts that ruled the Earth for 150 million years.

“I want to go back for a lot more,” Long said Wednesday. “It gets better every year.”