A group of men on a stag do in New Mexico found a rare three-million-year-old elephant skull, complete with its tusks, buried in sand at a popular tourist destination.
Antonio Gradillas and his friends were helping a man whose truck had become stuck in the sand at Elephant Butte State Park, when they came across the skull of the stegomastodon, Fox 15 reported.
They called the University of New Mexico to see what they should do with their find and were put in touch with paleontologist Gary Morgan, who went to investigate.
Mr Morgan, curator at the New Mexico Museum of Natural History and Science, led a team that spent six hours excavating the skull, which was buried in around four feet of lake silt.
They successfully removed the 1,000-pound fossil, which is about five feet by three feet and will take at least six months to clean.
"They discovered an ancient mastodon, fossil mastodon that is an elephant relative," said Mr Morgan. "We're looking at something that's three million years old here so it's a different kind of a mastodon, and the name 'stegomastodon' is the scientific name."
"This mastodon find is older than the woolly mammoth that tread the Earth in the Ice Age," he told Reuters. "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."
Mastodons - relatives of the elephant - stood 10 feet tall and migrated to North America around 15 million years ago, before becoming extinct about 10,000 years ago.