|Now that is what I call a party.|
The group of dudes came across the skull, complete with tusks, at the aptly named Elephant Butte State Park, 150 miles south of Albuquerque. Finding it buried in sand, they began digging until they realized what they had discovered. According to Reuters, the group then contacted a professor at the University of New Mexico, an unbelievably responsible and forward thinking thing for a bachelor party to do, who put them in touch with Gary Morgan. Morgan is a curator and paleontologist at the New Mexico Museum of Natural History and Science.
The procedure to fully excavate the fossil took six hours, as it was buried in four feet of lake silt. All told the skull measured 5 feet by 3 feet, and weighed over 1,000 pounds. Morgan to Reuters:
"This mastodon find is older than the woolly mammoth that tread the Earth in the Ice Age. ... It probably died on a sandbar of the ancient Rio Grande River. I've been here for 20 years and have never seen something like this before."
Museum officials praised the group for the wherewithal for realizing that they had found a valuable fossil (also for not destroying it.) Which given the fact of how the discovery was made, and the possible outcomes, was a small miracle in itself. Wedding guests praised the group for providing them with at least one thing to talk to acquaintances about during the reception.
It is unclear as to why the party was in the middle of the desert park during the bachelor party. Perhaps they were celebrating one last night of freedom by doing a little bit of amateur paleontology, and just got lucky. Odds are this is not the reason why, but that said, literally any possible explanation could be valid.