"Devil's Corkscrews," Niobrara River, Nebraska, USA,
In the late 1800s, a remarkable fossil discovery in what is now northwestern Nebraska captured the imagination of scientists and sparked decades of research.
At the Agate Springs quarries, paleontologists unearthed something entirely unexpected—giant, spiral-shaped fossil structures buried deep underground. These mysterious formations, often several feet tall and coiled like ancient tree trunks, were unlike anything seen before. Their peculiar shape and massive size puzzled researchers for years. What could they be?
Initially dubbed “devil’s corkscrews,” these structures were thought to be the fossilized roots of ancient trees or even the remains of giant freshwater sponges. But as investigations continued, a more grounded explanation emerged.
Scientists eventually determined that these spirals were actually burrows—complex underground dens created by an extinct genus of land-dwelling beavers known as Palaeocastor.
The construction of spiral burrows required more effort from paleocastorines than digging straight inclined passages of the same length. Among the reasons that led burrowing beavers to this form is their territorial crowding: in conditions of large colonies, straight burrows should have often intersected.
According to another assumption, the unusual shape of the burrows was a response to the hot and dry climate of that era. From this point of view, its spiral design could have been a kind of air conditioning system for maintaining an optimal temperature and humidity regime inside the nesting chamber, which was especially important for the successful breeding of offspring.
Today, the “devil’s corkscrews” remain one of North America’s most fascinating and bizarre fossil discoveries—a testament to the strange and adaptive behavior of prehistoric life, preserved in stone beneath the Nebraska prairie.
Photo by B. Nicholls
