But when an old manuscript turned up in Cairo, it contained the latitude and longitude of one of Stromer’s quarries. Smith and his colleagues were off. Having entered the wrong GPS coordinates, Smith quickly got lost in the desert southwest of Cairo. He stuck his head out his Toyota Land Cruiser to get oriented–and spotted one humongous bone. It turned out to belong to a titanosaur, a long-necked quadrupedal plant eater that lived during the Cretaceous period. It wasn’t just any dinosaur. This guy is the second most massive that scientists have ever discovered, the team reports in the journal Science.

The researchers named him Paralititan stromeri. The first part means “tidal giant,” for good reason: his upper arm bone measures more than five feet long, which means that he probably stretched 90 to 100 feet in length and weighed 150,000 to 160,000 pounds. Only Argentinosaurus, a titanosaur from South America, was heavier, but probably not longer. The skeleton lay in what was once a tropical mangrove swamp, figured geologist and team member Kenneth Lacovara of Drexel University. It’s not likely that Paralititan washed in there, since a carcass that huge would have floated through the shallow tidal channels about as well as the Sphinx up the road. This giant probably moseyed in under his own power. He wasn’t the only one. “The skeleton was spread around in sort of an odd way,” says Smith. “The pelvis was ripped apart, just torn to bits.” A nearby tooth belonged to the likely diner: the carnivorous Carcharodontosaurus.

What with the abundance of dino and other fossils at Bahariya, Smith says, “we may have stumbled on dinosaur heaven.” He and the rest of the team plan to return to the oasis at the end of this year. Of course, if they get the GPS coordinates wrong this time, too, who knows what they might stumble across.