06/17/2014 at 12:35 PM EDT
If only every bachelor party could be this groundbreaking.
On June 9, Antonio Gradillas and several friends were holding a bachelor party for their buddy Eric Pietryga at Elephant Butte Lake State Park, about 150 miles outside of Albuquerque, New Mexico.
"As we were walking we saw a bone sticking out about one or two inches from the ground," Gradillas told ABC News
With a little digging, that bone turned into a skull – a three million year old prehistoric skull
, to be exact.
Gradillas, 33, and his friends uncovered the skull and called a friend, who put him in touch with Gary Morgan, a paleontologist from the New Mexico Museum of Natural History and Science, who rushed to the scene with his crew Tuesday.
Morgan concluded that the skull could be from a prehistoric animal called a stegomastodon, which resembled a modern elephant. He says the one discovered by Gradillas was probably about nine feet tall, weighed over six tons and was around 50 years old when it died.
"This mastodon was living, drinking, feeding alongside the ancient Rio Grande 3 million years ago," Morgan told CBS affiliate KRQE
. The crew has so far only found the skull, not the rest of the creature's bones, but Morgan says the skull could be one of the best-preserved stegomastodon specimens in the U.S.
"This is the coolest thing ever," Gradillas said. "Some people with Ph.Ds in this field might not even have this kind of opportunity. We were so lucky."
Also lucky: Pietryga, who married Janel Clark Friday.