Randy Irmis is kneeling next to a prehistoric burial site in the walls of a canyon in the Utah desert.
Just inches under his fingertips is the skull of a 210-million-year-old creature entombed in the gritty sandstone. But as Irmis huddles on the narrow ledge and chips away at the block with a chisel and hammer, he notices—to his alarm—he has unearthed a crack.