Chemical analysis of mastodon tusks reveals the first signs of their annual migration

ANN ARBOR – About 13,000 years ago, during mating season, a male grouse was killed in a bloody battle with a competitor nearly 100 miles from its habitat range in what is now northeastern Indiana, according to the first study. which documented the annual migration. An individual animal of an extinct species. Thanks to the new technology, researchers at the University of Cincinnati and the University of Michigan at Ann Arbor are working to piece together the mysteries of these now-extinct animals. This eight-ton adult, known as mastodon Buesching, died when an opponent pierced the right side of his skull with the tip of a tusk, a fatal wound revealed years after his remains were found in 1998 on a farm. Near Fort Wayne. . Northeast Indiana is likely the favorite summer breeding ground for this solitary wanderer, who made the trip annually for the last three years of his life, heading north from his home in cold weather, according to an article published online June 13 in the Proceedings of the Academy National Science. The study also suggests that the mastodon may have discovered central and southern Michigan, which seems fitting for a creature with a life-size skeleton on display at the UM Museum of Natural History. “The unique finding of this study is that for the first time, we have been able to document the annual wild migration of an individual from an extinct species,” said Joshua Miller, a paleobiologist at the University of Cincinnati. “Using new simulation techniques and a suite of powerful geochemical tools, we were able to show that males of large animals such as Buesching migrate to breeding sites each year.”

MM University paleontologist Daniel Fisher holds a piece of well-preserved mastodon tusks (not Buesching’s mastodon). Image source: Jeremy Marple, University of Michigan News.

Daniel Fisher, a paleontologist and co-director of the study at UM, has been involved in the Buesching mastodon excavation for 24 years. For the study, he used a thin saw to cut a thin longitudinal slab from the center of the animal’s 9.5-foot-long right canine that resembled the shape of a banana, longer and better than the left. This tablet has been used in new isotope and life history analyses, allowing scientists to reconstruct where the animal lived during two key periods: adolescence and late adulthood. According to researchers, Buesching’s mastodon died at the age of 34 in a battle for his mate. “This tusk has a full life,” said Fisher, who has studied mastodons and mammoths for more than 40 years and helped excavate dozens of extinct species. Fisher, professor of earth and environmental sciences, said. Ecology, Ecology and Evolution Biology and Curator of the UM Museum of Paleontology. The team’s analyzes revealed that the Buesching mastodon home area was most likely in central Indiana. Like elephants today, the young males stayed close to the house until they separated from the female-led group when they reached their teens. As a single adult, Buesching used to travel longer distances and more frequently, covering roughly 20 miles a month, according to the researchers. In addition, it has moved with the seasons, including the root step north in a summer area that includes parts of northeastern Indiana, which is supposed to be used for breeding. In the harsh climates of the Pleistocene, migration and seasons may have been crucial to the reproductive success of mammals and other large mammals. However, according to the new study, little is known about how their geographic ranges fluctuate and shift seasonally or change with sexual maturity. Techniques for analyzing the ratios of different forms or isotopes of the elements strontium and oxygen in ancient canines are helping scientists unlock some of these secrets. Mastodons, mammoths, and modern elephants, which belong to a group of large mammals with flexible trunks called proboscis, have oblong incisor teeth that protrude from their skulls like tusks. Each year of the animal’s life, new layers of growth are deposited on top of the already existing ones, laid out in alternating light and dark strips.

The right half-tusk of a Buesching falcon. The numbers on the side of the tusk (12-14) indicate where the specific annual layers (from the tip of the tusk to the end of life at the base) appear on the surface of the tusks. Image source: Jeremy Marple, University of Michigan News.

Canine growth layers resemble ice cream cones, with a record of time of death at the base and time of birth at the tip. Mastodons were herbivores that fed on trees and shrubs. As they grew, chemicals from their food and the water they drank were incorporated into their body tissues, including their elegantly grown and sharpened fangs. In the newly published study, isotopes of strontium and oxygen in the growth layers of canines allowed researchers to reconstruct Buesching’s journeys as an adolescent and as a sexually active adult. They collected 36 samples from adolescence years (during and after leaving the maternal herd), and 30 samples from the last years of the animal’s life. Using a very small drill, operated under a microscope, half a millimeter is milled from the edge of individual growth layers, each of which extends from one to two months of the animal’s life. The dust produced during this process was chemically analyzed. The strontium isotope ratios in the tusks were geographic footprints associated with specific locations on maps showing changes in strontium across the landscape. Oxygen isotope levels, which reveal significant changes in seasons, helped researchers determine the time of year when a particular layer of canines formed. Because the strontium and oxygen isotopes samples were taken from the same limited growth layers, the researchers were able to draw specific conclusions about where Buesching traveled during different times of the year, and how old he was when he made the trip. Isotope data from the canines was entered into the geographic motion model developed by Miller and colleagues. The model allowed the team to estimate the animal’s distance traveled and movement possibilities between potential locations, something that had not been found in previous studies of extinct animals’ movements. “The field of strontium isotope geochemistry is a great emerging tool for paleontology, archaeology, historical ecology, and even forensic biology. It’s in bloom,” Miller said. “But really, we’re just beginning to see what this data can tell us. The next step in their research project, Fisher and Miller said, is to analyze canines from a different individual, whether male or female. The other authors of the PNAS study are Brooke Crowley and Bledar Konomi of the University of Cincinnati and Ross Secord of the Nebraska State Museum and University of Nebraska-Lincoln. The authors thank Kent and Jean Boishing for their donation of the Boishing Stone for Scientific Study, and the Indiana State Museum to allow access to the specimen.Financial support was provided by the University of Michigan, the University of Cincinnati Office of Research, the Minihaha Foundation, and the National Science Foundation (EAR-9628063). Mastodon use changed with maturity (late Pleistocene, North America)

Translated into Spanish by Luisa Sanchez, a political science student and Latin/Latin Studies student at the University of Michigan.