The "oldest fossil of a land animal ever found in Nevada" is believed to be a recently discovered doughnut-sized rock found only 20 miles from the Las Vegas strip.
The team also found some backbones and bone fragments, but is not sure what ancient creature the fossils belong to, the Las Vegas Review-Journal reported.
"It's something big," University of Nevada, Las Vegas paleontologist Josh Bonde, told Review-Journal. "These are great big vertebrae."
The fossils were found in a layer of rock believed to sat back to the Triassic period, which took place about 220 million to 230 million years ago.
The area where the fossil was found is believed to have been inhabited by strange crosses between mammal and reptile. Part of the area was also a covered by a shallow sea which the the ichthyosaur, which was as big as a school bus, called home.
Bonde suggested the impressive fossils could belong to a phytosaur, an early crocodile ancestor. He also believes they could have come from a metoposaur, which resembled an enormous amphibian.
"I don't know about you, but I think I'd be pretty terrified to be eaten by a giant salamander," Bonde told his volunteer crew, Review-Journal reported.
Harold Larson, an 84-year-old retired civil engineer, was the proud finder of the "rock," which was uncovered a few months ago. Larson said nobody believed him when he told them about the interesting fossil.
"To me it looked like fossilized bone," he told Review-Journal. "I doggedly knew it was bone of some kind. I wasn't going to give up on that. I wasn't going to be brushed aside."
When researchers finally did take a look they discovered the rock was indeed a fossil, which was older than 200-million-year-old dino footprints spotted nearby in 2010.
Bonde said he was "about 95 percent certain" the bones were the oldest known land animal remains ever found in the state.
