Posted November 21, 2014
Anterior view of the mastodon atlas.
Congrats to Dale and Bob who knew the right answer, and cryptically hid it in their responses, and to everyone else who guessed right or came awfully close! This is indeed the first cervical (neck) vertebra, also known as the atlas, of a mastodon. Why is it called an “atlas”!? Because of its position as the first vertebra, it in a sense it holds up the skull – reminiscent of Atlas of Greek mythology who held up the world. How do we know it’s a mastodon, and not a mammoth? Well, there is one clear difference between the two species. The dorsal tubercle, which is the upward projecting protuberance at the top of the photo, is more pointed in mastodons but very flat and broad in mammoths. Mastodon remains are also much more common in Ohio than mammoths, so it’s more likely that one would find a mastodon bone.
Atlas vertebra of mastodon compared to other species.
Compare the size of the mastodon atlas with the first vertebrae of an elk, wolf, and rhesus macaque monkey (photo). The scale is six inches. It’s interesting that the atlas is the only vertebra that doesn’t have a distinctly visible central portion, called the body. The atlas is basically a ring of bone. In most mammals though, an atlas body remnant of some size is present. The partner to the atlas is second cervical vertebra, known as the axis, and it fits neatly into the posterior side of the atlas (see illustration). This structure of the atlas and axis allows rotation of the head.
Atlas and axis of a human.
We’re glad that our anonymous donor not only decided to give the specimen to a museum but provided information about where this bone was found. When we know where and when an object is collected it becomes a specimen valuable to science, rather than a curiosity of which we know little about. Many very important finds of Pleistocene species in Ohio have been found by people during normal tasks such as digging to install drainage tiles or to enlarge a pond, or walking along a stream. So if you find bones or teeth, let us know! We’re always happy to identify such finds. Then if you decide to donate them to a museum, you’re not only making a contribution to science but your name will be attached to that specimen in perpetuity! A good example, the Conway mastodon!