13,600-Year-Old Mastodon Skull Uncovered in Iowa

Archaeologists have unearthed the well-preserved skull of a 13,600-year-old mastodon in south-central Iowa.

The creature may have crossed paths with Indigenous people, who began arriving in the area around the same time.

“The last glaciation probably still had the northern part of Iowa under ice,” says John Doershuk, Iowa’s state archaeologist, to Iowa Public Radio’s Zachary Oren Smith. “But the southern part was ice free at the time and was starting to vegetate and animals like mastodons were coming in to browse and human hunters would have also found that a hospitable place as well.”

Archaeologists spent 12 days excavating the skull in Wayne County, a rural area located roughly 80 miles south of Des Moines. The Office of the State Archaeologist learned of the specimen in the fall of 2022 after a man posted a photo of himself on social media.

“It was a photo of this relatively young guy,” Doershuk tells Radio Iowa’s Dar Danielson. “Huge grin on his face, holding a Fred Flintstone-type, you know, 45-inch long, massive bone.”

The bone, which was a mastodon femur, had been found in a creek bed on private property, according to the University of Iowa. Archaeologists visited the site in the fall of 2023 and also discovered a broken tusk protruding from the dirt. They suspected the tusk was still attached to a skull and began organizing this month’s excavation project.

In addition to the skull, archaeologists also found stone tools at the site. These artifacts date to a few thousand years after the mastodon’s death, but provide the first recorded evidence of humans in the region.

The team hope to find evidence that humans interacted with the mastodon, such as knives or projectile points used for hunting and butchering. They also plan to take a closer look at the skull itself, which might reveal cut marks made by humans.

The skull had a two-foot section of tusk still attached, which researchers hope will offer even more insights into this particular creature’s life.

“Apparently there are techniques now to determine how many calves a female mastodon had that get recorded as a chemical signature because of the changes in the body chemistry during the pregnancy and the birth,” Doershuk says to Iowa Public Radio. “And that gets recorded in the tusks.”

Moving forward, archaeologists and paleontologists plan to study and conserve the fossils. Eventually, the specimen will be displayed in a new exhibition at the Prairie Trails Museum of Wayne County.

Mastodons were hulking, shaggy creatures related to woolly mammoths and modern elephants. They roamed around the world starting in the Miocene (between 2.6 million and 23 million years ago) and went extinct around 10,500 years ago.

They stood up to 9.8 feet tall at the shoulders and had two long tusks that curved upward. Mastodons used their large, pointy teeth to grind up twigs, leaves and other plants. They were slightly smaller than woolly mammoths but similar in size to today’s living elephants.

Scientists continue to debate why mastodons and woolly mammoths went extinct, but they suspect climate change and human predation likely contributed to their demise.

The fossilized remains of mastodons and mammoths are relatively common in North America. In October 2022, a married couple in Alaska found a mammoth femur on the beach after a typhoon swept through the area. In June 2023, a woman walking on a beach in California found a molar tooth that once belonged to a mastodon. And earlier this month, a man found a 7-foot-long Columbian mammoth tusk in a Mississippi creek bank.

Researchers continue to use these fossilized remains to reveal new scientific discoveries. Earlier this summer, scientists used a piece of freeze-dried skin from a 52,000-year-old woolly mammoth to reconstruct the three-dimensional architecture of its DNA. Scientists have also used fossilized woolly mammoth tusks to show that the creatures went through musth, a period when their reproductive hormones surge.

Sarah Kuta | READ MORE

Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.