Paleontology in Idaho
Idaho continued to be a largely marine environment through the Triassic and Jurassic periods of the Mesozoic era, when brachiopods, bryozoans, corals, ichthyosaurs and sharks inhabited the local waters.
The eastern part of the state was dry land during the ensuing Cretaceous period when dinosaurs roamed the area and trees grew which would later form petrified wood.
Cenozoic Idaho had a more hospitable climate than it does today and would come to be home to huge forests and creatures like camels, early horses, mastodons, and sloths.
During the Pleistocene, short-faced bears, bison, camels, mammoths, saber-toothed cats, and giant sloths inhabited the state.
Contemporary local vegetation would leave behind fossils and coal deposits on occasion during the Carboniferous and Permian in areas of the state that had been uplifted above the water.
Like the state's Oligocene plants, its Miocene flora left behind abundant leaf imprints in near Coeur d'Alene and Moscow in the northern panhandle.
[4] During the ensuing Miocene epoch the northwestern United States was under an immense forest where beech, cypress, oak, and redwood used to grow.
Late Pliocene life of Idaho that was closely associated with water included aquatic birds, beavers, fish, frogs, a muskrat-like rodent, otters, and turtles.
Idaho's late Pliocene life which preferred drier habitats included camels, cats, hares, mastodons, peccaries, and sloths.
[8] The Pleistocene mammals of Idaho's American Falls Lake area included short-faced bears, bison, camels, mammoths, saber-toothed cats, and giant sloths.
[7] Other Quaternary life included birds, fishes, lizards, rabbits, rodents, mountain sheep, and snakes.
In 1904, several mammoth skeletons were found in a pocket of sand contained with a spring pool located on the east side of the river at American Falls.
These remains were shipped to diverse institutions including at the state capital in Boise, the University of Iowa, and the Smithsonian.
[7] Another notable early-20th century find occurred serendipitously at a farm: A farmer named Elmer Cook found a great number of late Pliocene fossils on his land.
Other fossils found at the site included beavers, fish, frogs, turtles, and other animals closely associated with water.
