More from the article...

... Researchers, who were alerted to the jaw-dropping scientific discovery in Orange County, spent about two and a half days digging at the home, uncovering more mastodon bone fragments and a complete adult jaw.

Mastodons are related to the modern day elephant and now-extinct mammoths. Historians say the ancient beasts lived across the Earth, but only fossils found in North America have been strictly identified.

"I'm thrilled that our property has yielded such an important find for the scientific community," the homeowner said in a statement. ...