National Geographic explorer-in-residence and paleontologist Paul Sereno announces the discovery of the Nigersaurus taqueti dino-saur during a news conference Thursday at the National Geo-graphic Society in Washington, D.C.

Chicago ? With a body as big as an elephant and a bizarrely toothy face at the end of a 6-foot neck, a skeleton unveiled Thursday by University of Chicago paleontologist Paul Sereno is making scientists reconsider the family tree of the giant plant-eating dinosaurs called sauropods.

Sereno and teams he led recovered fossilized bones of the beast on expeditions in 1997 and 1999 to a remote region of the Sahara Desert in the West African nation of Niger. It took eight years for scientists to piece together bones of many specimens in Sereno’s Chicago lab to get a nearly complete skeleton of the dinosaur, dubbed Nigersaurus taqueti.

Unveiled at the National Geographic Society headquarters in Washington, D.C., the skeleton finally puts a face and body on an animal that science previously knew only from a few scattered bones found elsewhere in Africa in the 1950s.

“Putting the whole thing together is a sort of a real eye-opener for paleontology,” said Thomas Holtz, a University of Maryland vertebrate paleontologist not associated with Sereno’s Niger expeditions. “This is a case of, after putting all the pieces of the puzzle together, the puzzle is more confusing than ever. The bits and pieces of Nigersaurus are weird, but seeing the whole thing together, it is even weirder.”

Nigersaurus’ strangeness begins at the end of its snout, which sports a squared-off jaw lined with 128 uniform front teeth. When it closed its mouth, a straight 10-inch row of 68 small teeth on the bottom met an equally straight row of 60 teeth on top, joining perfectly to snip plants the dinosaur ate.

“In modern mammals, when you see broad muzzles, you know that they are grazers, animals that eat grass, like cattle,” Sereno said. “When they have narrow, pointy snouts, you know they are browsers, animals that feed on leaves and bark they pull from trees and bushes, like giraffes.

“This thing was a Mesozoic cow.”

“Diplodocus is the next closest relative we are aware of to Nigersaurus,” said Sereno, lead author of a paper on Nigersaurus published in the online science journal Public Library of Science ONE.

It will also be featured in next month’s National Geographic.