in North America, Asia, and Europe. While the systematics (evolutionary relationships) of nodosaurids have not been firmly established, the genera Sauropelta, Silvisaurus and Pawpawsaurus are sometimes considered to be basal to geologically younger nodosaurids like Panoplosaurus, Edmontonia, and Animantarx. In a 2001 analysis, Carpenter included the former three genera in a sister clade to a group containing the latter three, although he found that Panoplosaurus could belong to either clade, depending which taxa and characters were chosen. Discovery and naming In the early 1930s, famed dinosaur hunter and paleontologist Barnum Brown collected the holotype specimen of Sauropelta (AMNH 3032, a partial skeleton) from the Cloverly Formation in Big Horn County, Montana. The locality is inside the Crow Indian Reservation. Brown also discovered two other specimens (AMNH 3035 and 3036). The latter is one of the best-preserved nodosaurid skeletons known to science, includes a large amount of in situ armor, and is on display in the American Museum of Natural History in New York City. AMNH 3035 preserves the cervical armor and most of a skull, missing only the end of the snout. Expeditions in the 1960s led by the equally renowned John Ostrom of Yale University's Peabody Museum of Natural History recovered additional incomplete specimens from the Cloverly. In 1970, Ostrom coined the genus Sauropelta to include remains discovered by both expeditions. Derived from the Greek () ('lizard') and πελτε () ('shield'), this name is a reference to its bony armor. Although Ostrom originally named the species S. edwardsi, nomenclaturist George Olshevsky corrected the spelling to S. edwardsorum in 1991 to conform to Latin grammar rules. Despite the naming of Sauropelta two years earlier, confusion arose in 1972 when the name "Peltosaurus" was inadvertently published as the caption of a photograph of AMNH 3036. Although Brown never published a name or description for the remains which are now known as Sauropelta edwardsorum, "Peltosaurus" was the name he informally used in lectures and museum exhibits. However, the name Peltosaurus was preoccupied by a genus of North American lizard from an extinct branch of the modern family Anguidae (the alligator lizards and the legless glass lizards) and is no longer used to refer to the dinosaur. In 1999, Carpenter and colleagues described material of a large nodosaurid from Utah, discovered in a member of the Cedar Mountain Formation called the Poison Strip Sandstone, which is contemporaneous with the Cloverly Formation. He originally