University of Michigan paleontologist Daniel Fisher with a mounted skeleton of the Bushing mastodon, based on castings made of individual bones made of fiberglass, is on public display at the Museum of Natural History at the University of Michigan in Ann Arbor. Credit: Eric Bronson, Michigan Photography
Mastodons are related to elephants belonging to the Mammut genus, which inhabited North and Central America before disappearing about 10,000 to 11,000 years ago. Typical adults are between 8 and 10 feet (2.5-3 m) tall at the shoulder and weigh about 8,000 to 12,000 pounds (3,600-5,400 kg). The largest open specimen is 10.7 feet (3.3 m) tall and weighs 24,000 pounds (11,000 kg). They lived in herds, feeding mainly on leaves and branches, much like modern elephants.
Although some evidence suggests that climate change may have contributed to their extinction, it is generally believed that human hunting by Paleo-Indians was a major factor in their extinction.
About 13,200 years ago, a wandering male mastodon died in a bloody battle during a mating season with a rival in present-day northeast Indiana, nearly 100 miles (160 km) from his home territory, according to the first study documenting annual migration of an extinct species.
The 8-ton (7,200 kg) adult, known as the Bushing mastodon, was killed when an opponent pierced the right side of his skull with the tip of a tusk, a deadly wound revealed to researchers when the animal’s remains were extracted from peat. a farm near Fort Wayne in 1998.
Northeast Indiana was probably the preferred summer place for mating for this lone traveler, who has been hiking annually for the past three years of his life, heading north from home during the cold season, according to a publication released today (June 13, 2022). ) in the Bulletin of the National Academy of Sciences.
The study also shows that the Bushing bull may have spent time exploring central and southern Michigan, which seems appropriate for a creature whose full-size fiberglass skeleton is on display at the Museum of Natural History at the University of Michigan at Ann Arbor.
“The result, which is unique to this study, is that for the first time we were able to document the annual land migration of an extinct individual,” said University of Cincinnati paleoecologist Joshua Miller, the study’s lead author.
“Using new modeling techniques and powerful geochemical tools, we have been able to show that large male mastodons such as Buesching migrate to mating sites each year.”
A skeleton of the Bushing mastodon, based on castings made of individual bones made of fiberglass, is on public display at the Museum of Natural History at the University of Michigan at Ann Arbor. The mastodon Buesching is an almost complete skeleton of an elderly man, restored in 1998 from a peat farm near Fort Wayne, Indiana. A new study led by Joshua Miller of the University of Cincinnati and Daniel Fisher of the University of Michigan uses oxygen and strontium isotopes from the mastodon’s right tusk to reconstruct changing patterns of landscape use throughout his life. Credit: Eric Bronson, Michigan Photography
UM paleontologist and co-leader of the study Daniel Fischer took part in the excavations of the mastodon in Bushing 24 years ago. He later used a band saw to cut a thin, longitudinal plate from the center of the banana-shaped 9.5-foot right tusk of the animal, which is longer and more preserved than the left.
This plate was used for new isotope and life analyzes, which allowed scientists to reconstruct changing patterns of landscape use during two key periods: adolescence and the last years of adulthood. Mastodon Bushing died in a battle for access to partners at the age of 34, according to researchers.
Daniel Fischer, a paleontologist and co-director of the University of Michigan study, participated in the excavations of the mastodon in Bushing 24 years ago. He later used a band saw to cut a thin, longitudinal plate from the center of the animal’s banana shape, a 9-foot right tusk. This plate was used for new isotope and life analyzes, which allowed scientists to reconstruct changing patterns of landscape use during two key periods: adolescence and the last years of adulthood. Mastodon Bushing died in a battle for access to partners at the age of 34, according to researchers. Credit: Photo courtesy of Daniel Fisher
“You have a lifetime scattered in front of you in this tusk,” said Fisher, who has studied mastodons and mammoths for more than 40 years and helped dig up dozens of missing elephant relatives.
“The growth and development of the animal, as well as its history of land use change and behavior change – this whole story is captured and recorded in the structure and composition of tusks,” said Fisher, a professor of land and environmental sciences. , Professor of Ecology and Evolutionary Biology and curator at the UM Museum of Paleontology.
The team’s analysis revealed that the original home of the mastodon Bushing was probably in central Indiana. Like modern elephants, the young male remained close to home until he separated from the female-led herd as a teenager.
As a single adult, Bushing traveled farther and more frequently, often traveling nearly 20 miles a month, according to researchers. In addition, the use of its landscape varies depending on the seasons, including a dramatic expansion to the north in a summer-only region that includes parts of northeastern Indiana, the alleged mating sites.
“Every time you reached the warm season, mastodon Bushing went to the same place – bam, bam, bam – many times. The clarity of this signal was unexpected and really exciting, “said Miller, who uses similar isotopic techniques to study caribou migration in Alaska and Canada.
The left half of the right tusk of the mastodon Bushing. The numbers on the side of the tusk (9-11) show where specific annual layers are found (counting from the top of the tusk to the end of life at the base) on the surface of the tusk. Credit: Jeremy Marble, University of Michigan News
In the harsh Pleistocene climate, migration and other forms of seasonal use of the landscape were probably crucial to the reproductive success of mastodons and other large mammals. However, little is known about how their geographical reach and mobility fluctuate seasonally or change with sexual maturity, according to a new study.
But techniques for analyzing the ratios of different forms or isotopes of the elements strontium and oxygen in ancient tusks have helped scientists uncover some of these secrets.
Mastodons, mammoths, and modern elephants, which are part of a group of large mammals with flexible trunks called proboscis, have elongated upper incisors that protrude from their skulls like tusks. During each year of the animal’s life, new growth layers are deposited on the already existing ones, located in alternating light and dark stripes.
A skeleton of the Bushing mastodon, based on castings made of individual bones made of fiberglass, is on public display at the Museum of Natural History at the University of Michigan at Ann Arbor. The mastodon Buesching is an almost complete skeleton of an elderly man, restored in 1998 from a peat farm near Fort Wayne, Indiana. A new study led by Joshua Miller of the University of Cincinnati and Daniel Fisher of the University of Michigan uses oxygen and strontium isotopes from the mastodon’s right tusk to reconstruct changing patterns of landscape use throughout his life. Credit: Eric Bronson, Michigan Photography
The annual growth layers in the tusks are somewhat similar to the annual rings on the tree, except that each new layer of tusks forms near the center, while new growth in the trees occurs in a layer of cells next to the bark. The layers of growth in the tusk look like an inverted pile of ice cream cones, with the time of death recorded at the base and the time of birth at the top.
Mastodons were herbivores that hunted trees and shrubs. As they grew, chemical elements in their food and drinking water were incorporated into their body tissues, including exquisitely sharpened, ever-growing tusks.
In a newly published study, isotopes of strontium and oxygen in the growth layers of tusks allowed researchers to reconstruct Buesching’s travels as an adolescent and as a reproductively active adult. Thirty-six samples were collected from adolescence (during and after leaving the matriarchal herd) and 30 samples were collected from the last years of the animal’s life.
In close-up, showing pieces of a tusk of a mastodon (not the mastodon Bushing), held by paleontologist at the University of Michigan Daniel Fisher. In Fisher’s right hand is a block near the base of the tusk, showing layers representing the last six years of life. A cross section of the tip of the mastodon tusk in Fischer’s left arm shows concentric annual layers of tusks. Credit: Jeremy Marble, University of Michigan News
A small drill, working under a microscope, is used to grind half a millimeter from the edge of individual growth layers, each covering a period of one to two months of the animal’s life. The dust obtained during this grinding process is collected and chemically analyzed.
The strontium isotope ratios in the tusk provide geographic fingerprints that are mapped to specific locations on maps showing how strontium changes in the landscape. Oxygen isotope values, which show marked seasonal fluctuations, helped researchers determine the time of year when a specific layer of tusks forms.
Because samples of strontium and oxygen areotopes were collected from the same narrow growth layers, the researchers were able to draw specific conclusions about where Bushing traveled at different times of the year and how old he was when he made each trip.
Tidal isotope data were then introduced into a spatially explicit motion pattern developed by Miller and his colleagues. The model …
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