Dr. Sharon Holte

Dr. Sharon Holte holds the skull of an adult bear found among the mammoths at the Mammoth Site. 

 

Mammoths are still among us, according to Dr. Sharon Holte, director of education at the Mammoth Site in Hot Springs, South Dakota. 

Last Thursday at the Ice Age Visitor Center at Wisconsin’s Interstate Park, Holte invited Ice Age enthusiasts to learn more about work the Mammoth Site is doing to not only uncover ancient animals from 140,000 years ago, but to examine them and gain more insight into the Ice Age period. 

The Mammoth Site was established in 1974 after housing developers discovered mammoth bones during their digging. When paleontologists Jim Mead and Larry Agenbroad were called in to begin excavation, Holte said, “They knew they had discovered something spectacular.” 

After uncovering a couple mammoths quickly, Mead and Agenbroad did not know that the count would be up to 60 mammoths in 2018. With the highest concentration of mammoths in the world, Holte explained that paleontologists wanted to know why the animal bones were gathered there. 

Developing the Mammoth Site as a nonprofit education and scientific research institution ensured the safety of the site in preserving and protecting it. In fact, the institute was built around the site, allowing excavation, research, tours and educational programming to occur inside. 

Holte noted one other benefit, “We left the skeletons and skulls where we found them, for everyone to enjoy.” 

As they excavated, a story about the mammoths slowly emerged. Over 140,000 years ago, the present Mammoth Site was a sink hole, measuring 67 feet deep and a quarter mile wide. During this time, the sinkhole filled with warm spring water. On cold days, many mammoths would enter the sinkhole to enjoy the water and when they tried to get out, the bottom and walls of the hole were too slippery for them to climb out. Over thousands of years, sediment filled the hole and hardened in to rock. 

In the ‘80s, Mead and Agenbroad wanted to know how old the site was. At the time, the most effective method was carbon dating, which estimated the site was 26,000 years old. However, a newer method of dating — optically stimulated luminescence or OSL — is more showed that the site is 140,000 to 190,000 years old. Using OSL, scientists can see how long a sample from the center of a rock has been exposed to the dark. According to Holte, the method has “proved to be really accurate.”  

But why were all of the mammoths young males? 

The best way to answer this question and other questions surrounding the climate and its effects during this time was to excavate neighboring caves for smaller animals. 

Why?

“Small animals can tell us what is going on with the environment,” Holte said. 

In 2015, the team began excavating the Persistence Cave in the Wind Cave National Park. During the dig, excavators found bones from rattle snakes, frogs, foxes, prairie dogs, bats, weasels, birds, bob cats, black bear, marmots, several species of rodents, horse, bison, camel, rabbits and pica. 

Many of these animals are not native to South Dakota anymore, illustrating Holte’s point that “each animal can tell a story about the past.” 

Those connections are still being researched. The team has expanded its research into the Greater Plains, digging up bison. Holte explained that bison are a keystone species and essential in understanding the Ice Period because there is a direct correlation between bison size and climate. For instance, Holte has determined that larger bison lived in colder climates while smaller bison existed in warmer ones. 

During her visit last week, Holte took the time to excavate bison in Becker, Minnesota, on the Snake River, which has now been deemed the Snake River Fossil Site. Many students from nearby schools took field trips to help with Holte’s excavation and found a plethora of bones, one of which was a bison femur that Holte showed during her presentation. 

Ongoing projects for Holte and her team include creating new exhibits highlighting animals and climate change, making the Mammoth Site more accessible for disabled individuals by installing elevators, widening the current staircase to the excavation site, continuing to 3Dprint and scan bones, and continuing children’s’ tours.  

Along with the site’s motto, “We Dig Big,” they also research big and will continue their work because learning what took place before the existence of man is pivotal in our understanding of life and the environment today.

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