Paleontology in Idaho facts for kids
Paleontology in Idaho is all about studying ancient life in the U.S. state of Idaho. Scientists look for fossils here to learn about plants and animals that lived long, long ago. Idaho's fossil record goes way back, from the time before complex life began, called the Precambrian era, all the way to more recent times.
Millions of years ago, during the Precambrian, tiny bacteria formed special layered rocks called stromatolites. Even ancient worms left their marks, called trace fossils, in the mud. For most of the Paleozoic era, Idaho was covered by a shallow sea. This sea was home to creatures like brachiopods (shellfish), corals, and trilobites (ancient sea bugs).
Idaho stayed mostly underwater through the Triassic and Jurassic periods of the Mesozoic era. In these waters lived brachiopods, bryozoans (tiny colonial animals), corals, ichthyosaurs (marine reptiles), and sharks. But during the Cretaceous period, the eastern part of Idaho became dry land. Dinosaurs walked here, and large trees grew, which later turned into petrified wood.
In the Cenozoic era, Idaho had a warmer climate than it does today. It was covered in huge forests and home to amazing animals like camels, early horses, mastodons (like elephants), and sloths. During the Pleistocene Ice Age, even bigger animals roamed Idaho, including short-faced bears, bison, mammoths, saber-toothed cats, and giant sloths.
By the early 1900s, scientists started paying close attention to Idaho's fossils. Important discoveries include several mammoth skeletons found in 1904 and a large collection of Pliocene fossils found in 1928. Idaho's official state fossil is the Hagerman horse, also known as Equus simplicidens, which lived during the Pliocene.
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Ancient Life in Idaho
The oldest fossils in Idaho are from the Precambrian era. Not much is known about life from this time, but scientists have found "trails" left by ancient worms in what is now Blackrock Canyon. Also, fossil stromatolites have been found in southeastern Idaho.
During the early Paleozoic era, Idaho was covered by seawater. Many different kinds of sea creatures lived here. In the Cambrian period, Idaho was home to early brachiopods and trilobites. Fossils from the Middle Cambrian in Caribou National Forest show that gastropods (snails) were also present. Sea levels changed a lot during the Silurian and Devonian periods, but most of Idaho stayed underwater.
Idaho remained flooded for most of the Carboniferous period. Areas like Arco and Mackay were underwater and full of marine life, especially corals. Both simple and complex corals were found. The state stayed mostly underwater through the Permian period, which was the end of the Paleozoic era. Sometimes, parts of Idaho were above water, and plants from these times left behind fossils and coal. In the Permian, interesting spiny brachiopods, corals, and tiny single-celled creatures called fusulinids lived in southeastern Idaho.
Idaho continued to be mostly a marine environment during the Triassic and Jurassic periods of the Mesozoic era. This sea was home to many invertebrates like brachiopods, bryozoans, corals, echinoids (like sea urchins), and molluscs. Larger animals included ichthyosaurs and sharks. However, the southeastern part of Idaho was sometimes dry land.
Dinosaurs and Ancient Plants
During the Cretaceous period, eastern Idaho had freshwater lakes and dry land. Freshwater environments were home to molluscs and tiny crustaceans called ostracods. On land, dinosaurs roamed among plants. Trees growing in southeastern Idaho during this time later turned into petrified wood. One of the most interesting plants from Cretaceous Idaho was the fern Tempskya.
Scientists have found signs of dinosaurs in Idaho, including possible armored dinosaurs, relatives of the horned dinosaurs, and possibly Tenontosaurus. Dinosaur eggs have also been found. There was a lot of volcanic activity in Idaho during the Cretaceous.
Life in the Cenozoic Era
As Idaho entered the Cenozoic era, its climate was likely warmer and more welcoming than it is today. Volcanic activity was still happening. During the Oligocene epoch, many plant fossils, especially leaf imprints, were preserved near Salmon. Similarly, in the Miocene epoch, abundant leaf imprints were found near Coeur d'Alene and Moscow in northern Idaho.
During the Miocene, the northwestern United States was covered by a huge forest with trees like beech, cypress, oak, and redwood. Volcanic eruptions covered a vast area with lava. Some of these trees were burned and preserved by the lava near Santa Creek, not far from Emida.
The Pliocene plants near Weiser also left many fossils, mostly leaf impressions. In the late Pliocene, Idaho was home to the horse Plesippus soshonensis. This horse is seen as a link between the older Pliohippus and the modern horse genus Equus.
Late Pliocene animals in Idaho that lived near water included aquatic birds, beavers, fish, frogs, a muskrat-like rodent, otters, and turtles. Animals that preferred drier areas included camels, cats, hares, mastodons, peccarys (pig-like animals), and sloths.
Hundreds of different life forms lived in Idaho during the Quaternary period. Many mollusc fossils, including freshwater clams, were found from the Pleistocene epoch. Pleistocene mammals in Idaho included Equus idahoensis, imperial mammoths, and musk oxen. The American Falls Lake area had short-faced bears, bison, camels, mammoths, saber-toothed cats, and giant sloths. Columbian mammoths were also present. Mastodons even got stuck in quicksand near Twin Falls. Other Quaternary animals included birds, fish, lizards, rabbits, rodents, mountain sheep, and snakes.
Fossil Discoveries
Important fossil discoveries in Idaho happened early in the 1900s. In 1904, several mammoth skeletons were found in a sand pit near American Falls. One amazing tusk found there was 15 inches wide at its base and over 15 feet long! These mammoth remains were sent to museums and universities, including ones in Boise, the University of Iowa, and the Smithsonian.
Another big discovery happened by chance on a farm. A farmer named Elmer Cook found many late Pliocene fossils on his land. In 1928, Dr. Harold collected hundreds of pounds of fossils from the Cook farm and sent some to the National Museum. Scientists from the Smithsonian Institution, J. W. Gidley and N. H. Boss, then led an expedition to the farm. They dug deep into a hill and found a huge amount of fossils.
Among the most important finds were horse bones, including skulls and jaws. The horse found here was later identified as a link between the older Pliohippus and the modern horse genus Equus. This Idaho horse was named Plesippus soshenensis. Other fossils found at the site included beavers, fish, frogs, and turtles, suggesting the area was once a watering hole. They also found fossils of aquatic birds, camels, cats, hares, mastodons, otters, peccaries, and sloths.
Idaho doesn't have as many dinosaur fossils as some other Western states, but scientists are finding more than they expected. One of the most common dinosaurs found is Oryctodromeus, a small dinosaur that could burrow into the ground. In 2023, Oryctodromeus was made Idaho's official state dinosaur. Notable dinosaur finds have been made in the Wayan Formation.
Places to Visit
Natural History Museums
- Idaho Museum of Natural History, Pocatello
- Orma J. Smith Museum, Caldwell
