Strange things have been known to happen at a bachelor party, some best left unmentioned, but a bunch of guys holding such an event in New Mexico has come up with a new one: finding a fossilized mastodon skull millions of years old.

The stag party participants, hiking near Albuquerque in Elephant Butte Lake Park, saw something looking like a bone sticking a few  inches out of the sand. When out of curiosity they began digging, they uncovered part of a perfectly preserved fossil skull.

"As we are cruising by we saw a large tusk, or what seems to be a large tusk, coming out of the ground about three to four inches," Antonio Gradillas, a member of the bachelor party, said.

Thinking it may have been from a wooly mammoth, they took some pictures and forwarded the snaps to the state Museum of Natural History and Science.

Museum researchers, upon seeing the pictures, realized it was an even more exciting discovery than a mastodon; the unearthed fossil was from a stegomastodon, an early ancestor of both prehistoric wooly mammoths and modern-day elephants.

The stegomastodon would have stood around 9 feet tall and weighed about 6 tons, museum paleontologist Gary Morgan said, and has been buried about 3 million years.

"This is far and away the best one we've ever found," Morgan said of the bachelor party's find.

Based on the size and shape of the skull, the ancient animal was probably around 50 years old at the time of its death along the banks of the Rio Grande River, he said.

Museum scientists, acting on directions from the bachelor party participants, traveled to the fossil site and spent almost six hours excavating a skull that was almost 5 feet long.

The skull, weighing almost a thousand pounds, was encased in plaster and taken to the museum for eventual public display, museum officials said.

First the fossil will need to be completely cleaned, a process that will likely take six months, after which scientists will study it in detail before it makes it public debut, they said.

"This mastodon find is older than the woolly mammoth that trod the Earth in the Ice Age," Morgan said. "I've been here for 20 years and have never seen something like this before."

Bachelor party attended Gradillas said he was well aware of the significance of the find.

"This is the coolest thing ever," he said. "Some people with PhDs in this field might not even have this kind of opportunity. We were so lucky."