Mastodon tusk reveals features of migration in North America

The mastodon fossil was first discovered on the farm in 1998 by Kent and Janne Büsching, who were mining peat on their property. Archaeologists then unearthed the remains of Buching’s mastodon. Its 9 feet (2.7 meters) tall and 25 feet (7.6 meters) long skeleton has been under study since 2006.

A closer look at the mastodon’s skull revealed that it was killed when the tip of another male mastodon’s tusk pierced the right side of its skull. He died about 100 miles (160 kilometers) from his home territory, according to a new study published Monday in the Proceedings of the National Academy of Sciences.

“The result, which is unique to this study, is that for the first time we have been able to document the annual terrestrial migration of an extinct species,” said study first author Joshua Miller, a paleoecologist and assistant professor of geology. at the University of Cincinnati, in a statement.

Northeast Indiana served as a summer mating ground for mastodons, and research has shown that this solitary creature migrated north from its home annually during the winter months for the last three years of its life. The researchers estimate that the ancient animal was about 34 years old when it died.

“Using new modeling techniques and powerful geochemical tools, we were able to show that large male mastodons like Büsching migrate to mating grounds every year,” Miller said.

Daniel Fisher, one of the leaders of the study, helped unearth the mastodon 24 years ago. He is professor of paleontology at the University of Michigan and director of the Museum of Paleontology at the University of Michigan.

Fisher carved a long, thin section from the center of the right tusk, 9.5 feet (3 meters) long. Similar to the study of tree rings, analysis of a mastodon’s tusk showed how it interacted with its landscape during adolescence, as well as in the last years of its life.

University of Michigan paleontologist Daniel Fisher stands with the skeleton of Busching's mastodon.  Photo by Eric Bronson, Michigan Photography.

“In this tusk, a whole life is spread out before you. The growth and development of the animal, as well as its history of land use change and behavioral change, all of this history is captured and recorded in the structure and composition of the tusk,” Fischer said.

When he was younger, the mastodon stayed close to home with his female-led herd in central Indiana before splitting off and going alone like modern elephants. As a lone rover, the mastodon traveled about 20 miles (32 kilometers) each month.

Tusk analysis

Migration was critical for mastodons to find places where they could breed while living in harsh, cold climates. But it was difficult for researchers to determine their geographic ranges.

Mastodons migrated vast distances due to climate change, study says

A search for isotopes of oxygen and strontium in mastodon tusks reveals some of these discoveries.

Mastodon tusks, like elephant tusks, have new growth layers that form closer to the center throughout their lives. Information about when they were born is stored on the tip of the tusk, and their death is stored in a layer at the base of the tusk.

As the mastodons chewed on bushes and trees and drank water, the chemicals from their food also accumulated in their tusks.

On the left half of the right tusk of Busching's mastodon are numbers indicating certain layers.  Photo by Jeremy Marble, University of Michigan News

Chemical analysis of tiny samples taken from different layers of Busching’s mastodon tusks correlated with geographic location, as the elements changed with the landscape as well as seasonal fluctuations. This data was incorporated into a movement model developed by the researchers to track when, where and how far he traveled.

“Each time you get close to the warm season, Busching’s mastodon has repeatedly headed to the same place – bam, bam, bam. The clarity of this signal was unexpected and truly breathtaking,” said Miller.

The researchers then want to study the tusks of other mastodons to see if they can make similar discoveries.

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