Historical Marker
The Judith River Formation
Chouteau County · Montana
The panel's claim of the first dinosaur fossils found overstates it: Hayden's were the first North American dinosaurs to be named. Leidy's unillustrated two-page paper of March 1856 placed these badlands in Nebraska Territory and named animals from teeth alone: Trachodon, for an Iguanodon-like plant-eater, Deinodon, the first tyrannosaurid teeth ever described, and Troodon, from a single tooth. One of Trachodon's seven teeth had a double root and later proved to come from a horned dinosaur. Trachodon and Deinodon are now doubtful names; Troodon is disputed. Nor was there a Geological Survey in 1855; it dates from 1879.
What the plaque says
The Judith River Formation In 1855, geologist Ferdinand V. Hayden explored the upper Missouri River for the United States Geologic Service. At that time, the area was the hunting ground of the Lakota, Blackfeet, Atsina, and River Crow Indians. A lone white man in Indian Country was often fair game to the tribes, but Hayden's passion for rocks and fossils earned him the name "He Who Picks Up Stones While Running" and a reputation for madness. The Indians left him alone. Hayden explored what would later become known as the Judith River Formation, a large area of sedimentary materials deposited in the lowland areas bordering the Colorado Sea during the Late Cretaceous Period 78 to 74 million years ago. During his exploration near the mouth of the Judith River, Hayden collected many fossilized teeth, bones, and shells from the Judith River Formation. He took them to anatomy Professor Joseph Leidy in Philadelphia for identification, who classified the teeth as belonging to a new species of hadrosaur. The teeth and bones were the first dinosaur fossils found in North America. Hayden's discovery drew paleontologists to Montana in search of dinosaur fossils and to the Judith River Formation making it a significant paleontological destination.
Where it stands
47.74222, -109.62690 · Directions
More markers nearby
- Fort Chardon — steps away
- The Judith Landing — 1.2 mi
- Camp Cooke — 1.2 mi
- Claggett Hill Trail — 1.9 mi