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More than 13,000 years ago, an American mastodon roamed what is today the American Midwest. Over the years, it has returned to an area in northeastern Indiana believed to be a mating ground. There he died in battle.
Where Mastodon spent his life and how he died was found by examining the chemical signatures recorded on his tooth. scientists reported Monday in the Proceedings of the National Academy of Sciences. Techniques offer a new perspective One of several ancient elephant relatives roaming North America before extinction.
The scientists studied the Buesching mastodon, which got its name from the family farm where it was found in 1998. view At the Indiana State Museum. Its tusks, also known as freds, record an animal’s entire life history, like modern elephants, and enable scientists to gather information from specific days, weeks, or years. Thus, scientists can sample areas in the female specifically from adolescence and adulthood and determine how its migration has changed over time.
This immigrant detective work focused on strontium and oxygen isotopes in teeth. University of Cincinnati paleoecologist and study author Joshua Miller defined strontium isotopes as leaving signals all over the landscape.
Strontium isotopes leach from rocks into the surrounding soil and water. As plants absorb these nutrients, they incorporate “these isotopic signatures.” Our hungry mastodon comes and eats those plants, stamping that geographical fingerprint on its teeth.
Interpreting these geographic references and matching them to the landscape takes it a step further: a map of how strontium isotopes vary in the terrain. build on writers work Other scientists, including Brooke E. Crowley of Cincinnati, and one of the co-authors of the study that created such a map.
Oxygen isotopes helped reveal the seasons in which Fred migrated. Each time it rained, the atmospheric isotopes that recorded the season were incorporated into local water bodies and swallowed up as water drank from nearby ponds and streams.
Combined with sophisticated statistical modeling, the team was able to determine this animal’s movement.
From the age of 29 to his 32nd year, things have changed drastically for this mastodon. Suddenly, he began to travel great distances with repeated signs of injury. But he continued to return to northeast Indiana each year—a place he had never explored in his teenage years, the authors noted. There, it wound up in late spring and early summer, an important clue that it might be a mating ground.
Daniel Fisher, a paleontologist at the University of Michigan and also author of the study, explained that the pits on the surface of the mastodon teeth are the only scar injury left behind. These wounds also leave an internal scar.
Dr. “These pits appeared to form where at some point in its growth history the female got stuck behind her bony socket,” Fisher said. When male proboscis thrusts their fangs into their opponents, the tooth is stuck back into the slot where it emerged from the skull. This affects ingrowth within the tooth and leaves marks as to what season the injury occurred.
The repetitive recurrence of these injuries in an adult male mastodon during the spring and summer led the team to suspect that it had undergone molt, a period of reproductive-related aggression seen in modern male elephants. sparring with other men is common.
Fatal craniofacial injury occurred in the same mating area during the same season.
“The methods they use are a broader trend To add much more detail in quaternary vertebrate paleontology behaviour and ecology One of those animals is Chris Widga, a vertebrate paleontologist and chief curator of the Gray Fossil Field in Tennessee, who was not involved in the research. “And this is the first time we have this data, which is really good.”
Whether migration patterns and injuries represent all male American mastodons is a question for future research. The team hopes to study more male and female mastodon fossils.
For now, the study opens the door to more questions: How did the migration patterns of female mastodons differ? Were there separate mating grounds for the various proboscisses coexisting at the time? Or, “Did they go to the same place and is this just a crazy area of hormone-laden tornadoes?” Miller asked. he thought.
Whatever the broader possibilities for mastodons as a species, Dr. Miller returned to the team’s explorations of the Buesching sample.
“Being at a point in geochemistry, modeling and paleobiology in general, where we can start to grasp some of these fundamental aspects of an individual’s biology,” he said, “I think it’s very, very deeply exciting.”
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