PHILADELPHIA, Pennsylvania (CNN) -- One of the two most massive dinosaurs ever known has been uncovered in a barren stretch of Egypt, scientists announced Thursday.
The 70-ton plant-eater was discovered in what is now the Sahara Desert. But eons ago the area was filled with mangrove swamps, said University of Pennsylvania researchers, who reported their findings in the May 31 edition of the journal Science.
When paleontologists dug up the first bone two years ago, a 5-foot-7-inch upper arm bone, they knew they had hit the jackpot -- it came from a giant dinosaur never seen before.
"It was very stocky. It was a big boy. It wasn't the longest. It wasn't the tallest. It was heavy," said University of Pennsylvania paleontologist Josh Smith, lead author of the Science report.
The animal weighed about 70 tons, and was perhaps 100 feet long. They named it Paralititan, meaning "tidal giant."
"It ate plants. It was one of the long-neck, long-tailed herbivorous dinosaurs we like to see walking around in herds off in the distance," he said.
Paralititan had some mean looking predators in its day, as big as and similar to the Giganotosaurus called Carcareadontisaurus, as big as the famous T. rex. But T. rex didn't come around until 30 million years later.
"I don't know how tall. He would look through a third story window without too much trouble," Smith said.
A difficult dig
Digging for bones in the Sahara desert wasn't easy. When Smith and his team found hip, leg and tailbones, they sometimes worked in punishing sandstorms that covered things up only seconds after they uncovered them.
"It was difficult. Getting the bones out of the ground was a real trial," he said. "There were days we couldn't work because we couldn't see."
The team came to the area known as the Bahariya Oasis because of noted German paleontologist Ernst Stroemer. More than 60 years ago, he found dinosaur bones there, but most of the area was destroyed in World War II.
Smith was trying to follow in Stroemer's footsteps, but got lost.
"And because I'm an idiot and can't read a map, we ended up in the wrong place," Smith said. "I had my head hanging out the window in the Land Cruiser and we drove right past the Paralititan site."
"The bone was sitting on the desert. We drove right by it. And I said, 'Hey, that looks like a bone.' And so we swung around and the rest is history. That giant one was sitting about a foot under the first bone that we saw."
Area once tropical
They were also surprised to discover the desert was once a lush tropical mangrove, similar to the Florida Everglades.
"We have forests that are actually growing in salt water. At the time Paralititan was alive, there was a coastline that ran through the center of Egypt," said Kenneth Lacovara, a geologist with Drexel University, in Philadelphia.
"They were some of the most powerful creatures to have ever lived and they dominated the planet for 140 million to 160 million years. If they could go extinct and if the Everglades could turn into the Sahara, then almost anything is possible in the future," he said.
The team hopes to return to Egypt. They don't expect to be lucky enough to find any more giants, but they anticipate a treasure trove of other plants and animals buried in the sand.
File Date: 5.31.01