ARLINGTON, Texas -- North Texas college students have stumbled upon the remains of a 100 million-year-old dinosaur -- a discovery so important that it could change the history books.

University of Texas at Arlington students Phil Kirchhoff and Bill Walker Jr. are credited with finding the remains of a duckbill dinosaur at an undisclosed location in Arlington.

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The graduate students' find is important for archeologists because it's the oldest hadrosaur fossil discovered, and it means that the dinosaurs could have originated in North America, as opposed to Asia.

"When we first found it, it was so big that we thought it was mammoth material because we have some of that material up there," Kirchhoff said. "We just couldn't believe we possibly found a dinosaur."

Just Wednesday, Kirchhoff and Walker found the spine of the hadrosaur, an amphibious dinosaur that had webbed feet and a bill.

"What we'd like to find is a complete hadrosaur skeleton," Walker said. "A complete skeleton has never been found."

The men said they were simply digging for turtle and crocodile remains on the stretch of land when he found the hadrosaur remains.