Largest dinosaur yet discovered in Argentina

Take the elephant, today's largest land-bound animal. Then stack 14 of them on top of one another. Then — and only then — would it be possible to conceive of the size of this mega-dino. It wasn't the fiercest dinosaur in the world. That title still belongs to the T. Rex. But this dinosaur — whose thigh bone alone dwarfs a fully grown man — was definitely the biggest.

"Given the size of these bones, which surpass any of the previously known giant animals, the new dinosaur is the largest animal known that walked on Earth," said Ruben Cuneo, who directs the Egidio Feruglio dinosaur museum in the Patagonian city of Trelew in southern Argentina, which is sponsoring the dig.

It will take researchers years of work to uncover the entire skeleton of the largest dinosaur ever discovered — a long-necked titanosaur as tall as a six-story building. "It's like two semi trucks, one after another," said José Luis Carballido, who led a team of researchers from Argentina's Museum of Palaeontology. "It's a real paleontological treasure. There were many and they were intact, which does not happen often."

And they'll need a new museum once they put it together. Paleontologists say the titanosaur could have stretched 66 feet tall and 132 feet long, weighing the equivalent of 14 or 15 adult African elephants. "Given the length and magnitude this animal will bring along when it's reconstructed, there won't be a building that can contain it. I think we're going to need a new home," Cuneo said.

Titanosaurs were a diverse group of sauropods, long-necked, whip-tailed gigantic plant-eaters that roamed the Earth more than 90 million years ago. Other experts agreed that this find is a previously undiscovered species and that it was at least as big as the Argentinosaurus, which had been thought to set the record for size at 70 tons.

Already, the complete thigh bone that they've uncovered is at 7.9 feet, the longest of any vertebrate yet found, Carballido said. A volumetric estimate based on the femur and humerus they've uncovered suggests the animal weighed around 176,000 pounds, he said.

"Based on what is known of the animal, it was certainly very, very large," agreed paleontologist John Whitlock of Mount Aloysius College in Pennsylvania.

Paleobiologist Paul Upchurch of University College London believes size estimates are more reliable when extrapolated from the circumference of bones. He said this femur is a whopping 43.3 inches around, about the same as the Argentinosaurus' thigh bone.

"Whether or not the new animal really will be the largest sauropod we know remains to be seen," said Upchurch, who wasn't involved in this discovery but has seen the bones firsthand. "Certainly the new animal appears to be at least as large as Argentinosaurus, and is a new species. Its real scientific value comes from the fact that it looks like this new form will be more complete than Argentinosaurus, so we'll get a better look at the anatomy of one of these super giants."

The bones were spotted years ago by a worker at a ranch outside the town of Las Plumas in Patagonia's Rio Chubut valley, and Carballido's team from the museum began digging in January 2013.

Cuneo said, "What they discovered is a cemetery of dinosaurs the likes of which we had never seen in the history of Argentine paleontology."

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