(Newser) – Many bachelor parties' participants get more than they bargained for, but for one group of revelers at Elephant Butte Lake State Park in New Mexico, what they got on Monday could turn out to be historic. "As we are cruising by we see ... what seems to be a large tusk coming out of the ground about a good three to four inches out," Antonio Gradillas tells KRQE News. So they did what any self-respecting young men in their prime surely would: They started digging. After unearthing what they thought was a woolly mammoth skull, the group sent photos to the New Mexico Museum of Natural History and Science in Albuquerque.

It turns out the fossil belongs to a stegomastodon, a 9-foot tall, 13,000-pound pachyderm that roamed New Mexico millions of years ago. Gary Morgan, a paleontologist with the museum, tells CBS News that in his 30-year career he has never seen a skull—which, being full of sand, could weigh 1,000 pounds—appear to be so perfectly intact. He headed up yesterday's excavation of the remains, telling the Las Cruces Sun-News that the skull of the elephant-like creature may be "the only complete one found in New Mexico." What Morgan was able to discern from the animal's teeth and location: That it likely perished 3 million years ago, around age 50. (Click to read about another really bizarre bachelor-party find.)

