Prehistoric Giant Unearthed: Massive Mastodon Skull Discovered in Rural Iowa Creek

In a stunning archaeological discovery, scientists have unearthed a remarkably preserved mastodon skull from a southern Iowa creekbed, the first of its kind in the state. Radiocarbon dating has since confirmed the ancient remains to be about 13,600 years old, and the animal has been affectionately nicknamed “Dolly” by the research team.

The 12-day excavation, carried out in August 2024, uncovered what experts described as a “goldmine” discovery. The mastodon skull, belonging to an extinct ancestor of today’s elephants, offers a glimpse into Iowa’s past and the megafauna that once populated the state. Mastodons stood roughly 10 feet tall at the shoulder and roamed North America from around 3.5 million years ago until about 10,500 years ago.

University of Iowa archaeologist Dr. Marshall Bassett, who worked on the excavation, said: “This is a once-in-a-lifetime find. It’s not just the first scientifically excavated mastodon in Iowa; it’s also incredibly well-preserved, which is rare for specimens of this age”.

The find is especially notable because its age overlaps with the period when people were first entering North America. That timing has researchers eager to look for evidence of interaction between early humans and the mastodon in the area.

Iowa State Archaeologist John Doershuk spoke about the find’s significance: “This mastodon likely lived during a time when humans were first entering North America. We’re eager to search for any evidence of human interaction with this individual”. He added that the team hoped to find traces such as projectile points and knives that might have been used to hunt or butcher the animal.

The discovery actually began two years before the main dig. In the fall of 2022, a local resident of Wayne County, in the southwestern part of the county near Corydon, alerted the University of Iowa Office of the State Archaeologist (OSA) to an unusually long bone embedded in a creek bed on private property. That bone turned out to be a mastodon femur. Archaeologists returned in the fall of 2023 and found a broken tusk protruding from the creek bed, which suggested the tusk might still be attached to a skull and prompted the full excavation. With grant funding from the Wayne County Foundation and donations to the Prairie Trails Museum of Corydon, the OSA team logged more than 1,000 hours of work and ultimately recovered the skull along with roughly 20 bone fragments — including ribs and a leg — likely all from the same animal.

The excavation also turned up several human-made artifacts, including stone tools. While those tools are dated a few thousand years after the mastodon lived, they document that humans inhabited the creek drainage, a previously unrecorded occurrence in that location. An article in Smithsonian Magazine noted that the creature “may have crossed paths with some of North America’s earliest human inhabitants,” adding to the excitement around the find.

Since the dig, the painstaking work of cleaning and preserving the remains has been under way at the OSA in Iowa City, where the bones are analyzed and conserved in partnership with the University of Iowa Paleontology Repository. Because the remains are only around 13,600 years old, they have not yet fossilized, leaving the bone comparatively fragile. University of Iowa undergraduate students have played a hands-on role, using soft brushes and distilled water in a slow process one of them likened to “reverse painting” to remove the dirt and clay still encasing the skull, which rests within sandbags and a wooden frame for support. The University of Iowa has also pursued further studies on the specimen, including radiocarbon dating and isotope analysis aimed at revealing more about the diet and environment of the mastodon.

Once the conservation work is complete, Dolly is set to find a permanent public home close to where she was unearthed. Under an agreement among the museum, the landowner, and state archaeologists, the remains will be displayed at the Prairie Trails Museum of Wayne County in Corydon on a 10-year loan, renewable every five years. Museum director Brenda DeVore, who has called the project the highlight of her career, anticipates the bones being installed in the summer of 2026, accompanied by educational exhibits and even 3D-printed bones that visitors can touch. Doershuk has noted that discoveries like this one may become more common as natural erosion exposes long-buried remains.

The discovery of this mastodon skull is a reminder of the geological and biological wealth that lies below the earth we walk on, waiting to be uncovered. As researchers continue to study the specimen, there is much still to learn about the world that once existed in the heart of America.