Ice Age Ohio would have been a great place to go on safari. You might have seen two kinds of elephants, mammoths and mastodons, the latter quite common and the former rather rare. You might have seen musk oxen that looked like goats but were the size of bison, which you also would have seen, including a species with horns that spanned 6 feet.

Peccaries, pig-like animals closely related to the modern javelina of the American Southwest, would have been common. The stag-moose, looking like a cross between a moose and a very large deer, might have made an appearance. If you were really lucky (or unlucky), you might have encountered the short-faced bear, larger than a modern grizzly. The strangest sight would have been the giant ground sloth, like nothing living today.

You might also have seen beavers, but not just the species you expect to see today. There used to be a beaver the size of a black bear, perhaps 6 feet long and weighing 200 pounds. Its scientific name is Castoroides ohioensis. It was discovered around 1830 when workers were digging a canal just north of Nashport in Muskingum County. Since then, it has been found in at least 17 other locations around Ohio and over much of North America, from Florida to the Yukon and from Nebraska to New York.

It was a bit different from the modern species, in more ways than size. Its tail wasn’t as flat, and its front teeth didn’t have such chisel-sharp tips. Unlike the living beaver, there is no evidence that it cut down trees and built lodges but instead was thought to have lived more like a muskrat, living in or near bodies of water. The recent research supported that.

The research was based on isotopes. All atoms of a particular element have the same number of protons in their nucleus; for example, calcium has 20. But different atoms of the same element might have different numbers of neutrons, the other part of the nucleus. For calcium, that number can range from 20 to 28. Those different “varieties” of the same element are called isotopes.

Different kinds of plants are characterized by different relative amounts (or ratios) of various isotopes, including carbon and oxygen. Those ratios are passed on to the animals that eat those plants and are incorporated into their bones. By measuring those ratios, scientists can determine what kinds of plants those animals ate.

The recent research showed that the giant beaver, unlike its modern counterpart, was not eating bark and twigs. It was eating mostly aquatic plants like pondweed and water lilies.

When things got drier at the end of the Ice Age, the giant beaver became extinct. The modern beaver, which could make its own wetlands by building dams, survived.

Dale Gnidovec is curator of the Orton Geological Museum at Ohio State University.

gnidovec.1@osu.edu