A University of Michigan study has used a new type of technology to help determine the migration patterns of mastodons . By analyzing isotopes from the tusk of an Ice Age mastodon, the researchers determined that it died in northeastern Indiana, nearly 100 miles north of its cold-season home range.
“The unique result of this study is that, for the first time, we have been able to document the annual terrestrial migration of an individual of an extinct species,” explains Joshua Miller, paleoecologist at the University of Cincinnati and leader of the study published in the journal Proceedings of the National Academy of Sciences.
mating battle
To explore mastodon migration patterns, the researchers used new isotope technology and a new model developed by Miller and colleagues to analyze the growth rings of the prized mastodon tusk . The growth layers on a tusk resemble an inverted stack of ice cream cones, with the time of birth and death recorded at the tip and base, respectively. (They are similar to the annual rings of a tree .)
The banana-shaped tusk of Buesching the mastodon, just under 3 meters long, was carved with a band saw to uncover clues that would lead to the annual migration activities of this animal. They were able to extrapolate where the animal was during its adolescence and later adult life before its death at age 34 by specifically using strontium and oxygen isotopes in tusk growth layers to recreate the behemoth’s adventures and environments.
“The field of strontium isotope geochemistry is a really promising tool for paleontology, archaeology, historical ecology and even forensic biology. It’s flourishing,” Miller said. “But really, we’ve only scratched the surface of what this information can tell us.”
According to experts, the extinct animal died 100 miles from its home in a bloody mating-season battle 13,200 years ago in what is now northeastern Indiana. He was apparently fatally injured after the tip of another mastodon’s tusk pierced the right side of his skull. Thousands of years after his death, this behemoth still had a story to tell.
“You have a whole extended life in front of you in that tusk,” said Daniel Fisher, a co-author of the paper, who has studied mastodons and mammoths for more than 40 years and helped excavate several dozen of the extinct elephant relatives. “The growth and development of the animal, as well as its history of land use changes and behavioral change, all of that history is captured and recorded in the structure and composition of the tusk.”
Looking for a partner
They used a spatial computer model to estimate how far the animal moved and identify likely locations. The tusk fragment revealed that, like elephants today, Buesching’s environment was much the same until he reached adolescence, at which point he was likely expelled from his female-led herd and exhorted to seek his own family.
After some time wandering alone (on average, it did 30 kilometers a month as a solitary adult), analysis indicates that the mastodon began to make annual trips to northeast Indiana, at least three times before dying. Their use of the landscape also varied seasonally with a dramatic northward expansion in summer that included breeding grounds.
The next step is to analyze the tusks of a different individual, either another male or a female.
The full-size fiberglass skeleton of this Ice Age mastodon is on display at the University of Michigan Museum of Natural History in Ann Arbor.
Referencia: Joshua H. Miller, Daniel C. Fisher, Brooke E. Crowley, Ross Secord, Bledar A. Konomi. Male mastodon landscape use changed with maturation (late Pleistocene, North America). PNAS, 2022 DOI: 10.1073/pnas.2118329119
