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Paleontology in Wyoming

BLM Wyoming manages about 18 million acres of public land. Fossils from Wyoming range from the two billion year old traces of blue-green algae that once lived in Precambrian seas to the 13,000 year old Ice age mammoths of the Pleistocene. Wyoming is world renowned for the fossils preserved on its public lands. These include perfectly preserved leaves and flowers, dinosaur and pterosaur footprints from an ancient beach, schools of perfectly preserved fish, forests of ancient redwoods, shrew-to-elephant –sized mammals, and the oldest known parrots and horses, as well as some of the most popular dinosaurs in the world (e.g. Tyrannosaurus rex, Allosaurus, Stegosaurus, Triceratops, Apatosaurus (Brontosaurus), Diplodocus and Deinonychus).

Because of the abundance of fossils in Wyoming, for over 150 years scientists from around the country have traveled to this area to explore, discover, and collect the rich paleontological resources located here. Fossils from Wyoming have and remain pivotal in our understanding of life on our planet and many scientific concepts related to evolution and environmental change come from fossils found in the state. In addition, fossils from Wyoming’s public lands are currently on display in museums around the country.

5 researchers walk among a string grid system set up at the bottom of Natural Trap Cave.

Natural Trap Cave is an internationally known cave because it has the largest collection of cave fossils in the U.S. Unsuspecting animals fell into the small cave opening, creating a mound of remains mixed with sediment that measures approximately 15 feet. Thousands of specimens—including pikas, jackrabbits, red foxes, short-faced bears, weasels, American cheetahs, American lions, deer, bison, bighorn sheep and mammoths—were recovered during excavations conducted nearly 30 years ago by the University of Kansas. After multiple years of planning, scientists re-entered Natural Trap Cave in July 2014, looking for bones and teeth, hopefully containing DNA. Analysis relative to the genetics of these Ice Age animals will employ techniques that weren’t available in the 1980s.

An Allosaurus skeleton is displayed in a museum.

'Big Al' is the name given to a juvenile Allosaurus fragilis skeleton found on BLM-administered land in 1991. Big Al was a carnivorous dinosaur, which lived in the Late Jurassic of northern Wyoming around 145 million years ago. The skeleton was found near the famous Howe Quarry in the Morrison Formation. The skeleton was unusually well preserved with over 95 percent of his bones found that were in the same positions as when it died. Big Al had many injuries which occurred in the last few years of his life. Piecing together the evidence from these bones and those of other animals found in the Morrison Formation, a story of how Big Al may have lived and died was developed.

Close up of two three-toed dinosaur tracks.

The Red Gulch Dinosaur Tracksite is the largest tracksite in Wyoming and one of only a few worldwide from the Middle Jurassic Period (160 million to 180 million years old). Until the tracks were reported in 1997, most scientists thought the entire Bighorn Basin and most of Wyoming was covered by an ancient ocean called the Sundance Sea. Scientists thought that only sea-dwelling creatures could have lived in this area. There shouldn't be any dinosaur footprints at all. Not only are there hundreds of tracks, but in this 40-acre area there could be thousands. The dinosaur tracks were clearly made just at the shoreline, not in deep ocean water, and there must have been large areas of dry land to support not only dinosaurs but other animals and plants.