PHILADELPHIA — Eighty-five feet long, 30 feet tall, 130,000 pounds and still growing when it died, a newly described dinosaur is among the largest land animals that ever lived — so big its discoverers are calling it the Dreadnoughtus. Its skeleton, unearthed in the Patagonia region of Argentina, is the first of this species and the most complete ever found in the group of gargantuan dinosaurs known as titanosaurs, scientists reported on Thursday. An international team led by Kenneth J. Lacovara, a paleontologist at Drexel University in Philadelphia, describes the fossil in the journal Scientific Reports. “What we can say with certainty is this is the biggest land animal that we can actually put a number on,” Dr. Lacovara said. Even what remains of the bones is huge. “We’ve got 16 tons of bone in my lab right now,” Dr. Lacovara said. Continue reading the main story Featured Comment ACW New Jersey Science, yet again, produces far more fascinating and improbable phenomena than the human imagination can manage. 75 Comments Write a comment The better-known Brachiosaurus weighed only 75,000 pounds; an empty Boeing 737-900 weighs about 93,700 pounds. A male African elephant, the largest land animal today, weighs a minuscule 15,000 pounds by comparison. (Blue whales dwarf all land animals, past and present, growing to 300,000 pounds.) Most titanosaurs are known from only a few bones. The vertebrae along the backbone of Argentinosaurus, a titanosaur that some claim to be the biggest of dinosaurs, are larger than those of Dreadnoughtus, but crucial bones needed to accurately estimate its mass have not yet been found. With Dreadnoughtus, the researchers have more than 200 bones, representing 45 percent of the skeleton and 70 percent of the bones behind the head. That includes the left thighbone, more than six feet tall, and an upper-arm bone, which allowed a calculation of the weight of 130,000 pounds, or 65 tons. “It’s a pretty good one,” said Patrick O’Connor, a professor of anatomy at Ohio University, who was not involved with the new research. “Most often they’re not anywhere this complete.” This Dreadnoughtus appears to have been an adolescent. From the microscopic bone structure, the researchers deduced that it had yet not reached its full-grown size when it died, sometime between 84 million and 66 million years ago. “I think they put together a solid argument,” Dr. O’Connor said of that conclusion. “I think it will engage a lively debate.” The skeleton currently fills most of Dr. Lacovara’s laboratory at Drexel. The vertebrae of the 30-foot tail stretch along a table by one wall, then turn the corner to continue along the next wall. The part of the bones that connected to the muscle that wagged the tail is notably heftier than that in other titanosaurs. “It seems to be muscled even more than you might expect,” Dr. Lacovara said. “Over here, we have a single vertebra from the neck of this guy,” he said, pointing to a three-foot-diameter bone on the floor that he said was from halfway up the 37-foot neck of Dreadnoughtus. “It gives you an idea just how big this animal was.” He then picked up what looked like a fossilized piece of rope. “We actually have what we believe are neck tendons, preserved,” he said. Many of the bones, like the ribs, are hollow. In modern animals, body weight roughly correlates with the internal body temperature. “If you put 65 tons on that graph, it would be a temperature way above the temperature that would cook meat,” Dr. Lacovara said. The hollows likely contained air sacs that connected to the respiratory system and allowed titanosaurs to essentially fan themselves on the inside, he said.