FOR RICH AND Annette Schneider of Portland, Mich., the digging of a new pond in their backyard suddenly turned into an excavation of ancient bones, as they uncovered parts of a grown mastodon — a mammoth-like creature that entered the North American continent about 15 million years ago.

"We pulled up a thigh bone and we knew there was something going on. We didn't know what was going on, but quickly started pawing through the excavated dirt and found rib bones, a tusk and more," Rich Schneider told MichiganScience. "Everyday we went out there, we found more pieces, including some that were still embedded in the pond bed itself."

The mastodon in question is believed to be about 10,000 years old, from right around the time the species went extinct. Professor Daniel Fisher from the University of Michigan studied the excavation and bones and believes the animal was most likely killed by humans and butchered. The bones are believed to have been placed in a pre-existing pond by Paleo-Indians who arrived on the continent around 13,000 B.C. and would submerge part of their captured prey in water to store it for later use.

"We thought it was the right thing to donate the bones to science, since the scientists can extract a wealth of information from them and do a lot better with them than we can," Schneider said.

Fisher is very grateful for the donation and hopes to learn a lot from the bones and tusk. Specifically, they may reveal information on the general health of the animal, since a large debate surrounds how mastodons actually became extinct. Some scientists believe they died out as a result of climate changes and subsequent food scarcity, which would be revealed in the fossilized remains of the mastodons. For the most part, however, this has not been the case, and Fisher believes instead that they were hunted to extinction by humans who may have specialized in big-game hunting. A mastodon would be the size of a present-day elephant, but more heavily built and easily weighing about six tons.

"Would it be hard to hunt down a mastodon? Well, it would be hard for you and me. But in terms of what they (Paleo-Indians) were capable of doing, I don't think there is any question they were capable of hunting these animals," Fisher told MichiganScience. "Whether they did so systematically is a controversial issue though."

This is not the first time mastodon remains have been found in Michigan. In the last 100 years, parts of about 250 mastodons have been uncovered in Michigan. In 2007, archeologists discovered a boulder in Grand Traverse Bay with what looked like drawn markings resembling a mastodon with a spear in its side, indicating that humans hunted them frequently.