On public land near Shell in Big Horn County, Wyoming, along the Red Gulch/Alkali National Back Country Byway, a limestone layer holds the footprints of dinosaurs that walked the shore of the Sundance Sea 160 to 180 million years ago. The research geologist Erik Kvale of the Indiana Geological Survey found them in 1997, and they came as a surprise, because the Sundance Formation had long been thought purely marine; the layer just above the tracks is full of Gryphaea shells, showing the sea came back later. The tracks seem to come from a large and varied group of dinosaurs, some probably theropods, but Middle Jurassic theropods are so rare that nobody knows what made them. Most of the prints are on a stretch nicknamed the ballroom. Belemnites, crinoids and fossil shrimp burrows lie in the rock as well. The Bureau of Land Management keeps the tracksite open to the public.
Middle Jurassic footprints on an ancient shore · Middle Jurassic, 160-180 mya
This ground is protected. Photograph it, record it, leave it where it lies. On US federal land the Paleontological Resources Preservation Act 2009 makes collecting vertebrate fossils an offence, and penalties are real.
Other places on the map within a couple of hours.
