referred it to Sauropelta as a possible new species, but it was never named. In more recent publications, Carpenter no longer refers the Poison Strip animal to Sauropelta, only to the family Nodosauridae. Other recent, but undescribed, discoveries include a complete skull from the Cloverly of Montana and a huge fragmentary skeleton from the Cedar Mountain Formation of Utah. These discoveries have been published only as abstracts for the annual Society of Vertebrate Paleontology conference, and may or may not prove to belong to S. edwardsorum or even Sauropelta when formally published. Footprint discoveries In 1932, Charles Mortram Sternberg reported the presence of the footprints of a large, four-footed dinosaur from Lower Cretaceous rocks in British Columbia, Canada. He described a new ichnogenus and species for these tracks, Tetrapodosaurus borealis, and attributed them to ceratopsians. However, in 1984 paleontologist Kenneth Carpenter re-examined the British Columbian Tetrapodosaurus prints and argued that they were made by ankylosaurs rather than ceratopsians. Specifically, Carpenter concluded that these were probably the footprints of Sauropelta. Five years later, large numbers of Tetrapodosaurus tracks were discovered at the Smoky River Coal Mine near Grande Cache, Alberta. This site is considered the most important ankylosaur track site in the world. Paleoecology Sauropelta was one of the earliest known nodosaurids. All specimens of S. edwardsorum were recovered from the Little Sheep Mudstone section of the Cloverly Formation in Wyoming and Montana, which has been dated to 108.5 million years ago, during the Early Cretaceous. Sauropelta lived in wide floodplains around rivers that drained into the shallow inland sea to the north and east, carrying sediment eroded from the low mountains to the west. Periodic flooding of these rivers covered the surrounding plains with new muddy sediments, creating the Cloverly Formation and burying the remains of many animals, some of which would be fossilized. At the end of Cloverly times, the shallow sea would expand to cover the entire region and would eventually split North America completely in half, forming the Western Interior Seaway. Abundant fossil remains of coniferous trees suggest that these plains were covered in forests. Grasses would not evolve until later in the Cretaceous, so Sauropelta and other Early Cretaceous dinosaurian herbivores browsed from a variety of conifers and cycads. Nodosaurids like Sauropelta had narrow snouts, an adaptation seen today in animals that are selective browsers as opposed to the wide muzzles of grazers. While Sauropelta was