Paleontologist Kenneth Lacovara examines bones of a Dreadnoughtus schrani at Drexel University in Pa. (Jacqueline Larma / AP)
Philadelphia— It weighed as much as eight school buses.
Its neck looked like a section of oil pipeline. Its thigh bone alone was as big as a grown man. The four-legged beast, with a powerful 29-foot tail, stretched about 85 feet long.
Say hello to Dreadnoughtus schrani.
In many cases, the fossils of giant dinosaurs are largely incomplete, preventing scientists from making good estimates about their size, movement and other characteristics. Scientists were able to recover close to 70 percent of the dinosaur’s 250-odd bones in southern Patagonia in Argentina.
Paleontologist Jeff Wilson at the University of Michigan called the finding “a really great specimen.”
Among the questions the skeleton can help scientists investigate, he said, is what kind of anatomical features were needed to let a dinosaur grow so huge.
By measuring the circumference of the thigh bone and upper arm bone, the researchers calculated that this beast weighed more than 65 tons. And it was not done growing, as evidenced by shoulder bones that had yet to fuse together, said team leader Kenneth Lacovara, an associate professor of paleontology and geology at Drexel.
Lacovara, who found the specimen in Argentina’s southern Patagonia in 2005, said he can’t claim it was the most massive dinosaur known, because the remains of comparably sized beasts are too fragmentary to allow a direct comparison.
Lacovara and colleagues describe the plant-eating behemoth in a study released Thursday by the journal Scientific Reports. He said the bones were probably around 75 million to 77 million years old.
He named the animal after the dreadnought class of battleships from the early 20th century, so nicknamed because they feared nothing — dreaded naught. This dinosaur was so big that few predators would have dared to attack it, Lacovara said. But if one of them did, the dinosaur could have responded with a smack of its muscular tail.
“It essentially had a weaponized tail,” Lacovara said.
The “schrani” portion of the name is a tribute to Philadelphia tech entrepreneur Adam Schran, who helped fund the research. Dreadnoughtus schrani belongs to a poorly understood group of dinosaurs called titanosaurs.
The new find will contribute to scientists’ understanding of how the biggest land animals moved, and how they could sustain themselves — likely by gorging on tens of thousands of calories’ worth of leaves and plant matter every day, Lacovara said.
The creature got some media attention in 2009 when its excavated remains arrived in a large shipping container at a pier in Philadelphia. Since then, Lacovara and colleagues have created computerized 3D reconstruction of the bones, and have started making miniaturized physical models of parts of the skeleton to investigate how the animal moved.
The bones will be returned next year to Argentina, where they will be housed permanently at a museum, researchers said.
Experts not connected with the study said the remains were remarkably complete and well-preserved for a titanosaur, although no complete skull was found.
“We’re getting a more complete picture of this giant animal than we have for any of the other big titanosaurs that are out there,” said paleontologist Kristi Curry Rogers of Macalester College in St. Paul, Minnesota. The bounty of anatomical data should help scientists learn about variation in titanosaurs and their evolution, she said.
“This is pretty big news,” Rogers said.
Last May, other scientists announced that another huge dinosaur was being excavated in Patagonia. Wilson, who has seen some of its bones, said its size is comparable to Dreadnoughtus. He said he hopes scientists can determine whether the two beasts are related, or whether each came by its huge size independently.
Paul Upchurch of University College London said he thinks the recently announced dinosaur and another species, Argentinosaurus, were more massive than Dreadnoughtus. But he called Dreadnoughtus valuable for its combination of size and the completeness of its skeleton.
“If you’re interested in super gigantic animals, this is probably the one you want to work on” to study how such beasts walked around, Upchurch said.
Associated Press contributed.