Sixty-five million years ago, Tyrannosaurus rex and countless other dinosaur species roamed what is today northwest South Dakota. Kayleigh Johnson, Museum of Geology laboratory manager and preparator at South Dakota Mines, is working to conserve a jaw discovered alongside the skull and other elements of a T. rex in the early 1980s near Mud Butte, SD – the sixth T. rex specimen ever to be discovered in the world. Johnson will discuss the history of the "Mud Butte" specimen and the materials and methods she is using to conserve the jaw.