Between 1891 and 1904, research teams from the University of Nebraska and the Carnegie Museum excavated many Daemonelix spirals. Initially believed to be the fossil remains of gigantic plants, they were later identified as fossilized casts of spiral burrows made by ancient beavers called Palaeocastor. A Palaeocastor skull was found inside a corkscrew burrow. This plant-eating rodent had deep-rooted teeth that continued to grow as they wore down, using those teeth to dig the spiral burrows while powerful forelimbs pushed dirt behind. Dr. Erwin H. Barbour of the University of Nebraska developed the plant theory about Daemonelix and, because of his preoccupation with it, narrowly missed discovering the Agate bonebed while here in 1892. Olaf A. Peterson of the Carnegie Museum in Pittsburgh disproved Barbour's plant theory when he found fossil beaver skeletons within the spiral burrows.