Wyoming holds more dinosaur records than any other state in the database: 938, led by Triceratops, Allosaurus, Stegosaurus and Diplodocus. Most of its 29,749 fossil records are not dinosaurs, though. 21,207 of them come from the Paleogene.
The dinosaurs sit in two sets of rock. The Morrison Formation, laid down by Late Jurassic rivers about 150 million years ago, holds the long-necked sauropods and the predator Allosaurus. Como Bluff, worked by the rival collectors Cope and Marsh from 1877, was one of the first big quarries. In the east, the Lance Formation preserves the last dinosaurs before the extinction. John Bell Hatcher collected the Triceratops skull there in 1888 that Othniel Marsh used to name the genus the next year.
The Paleogene record is a different world. In the Eocene a subtropical lake covered the southwest corner of the state, and its mud buried fish by the thousand. Knightia, a herring relative about 10 cm long, is the most commonly dug fossil fish on Earth and Wyoming's state fossil. Fossil Butte National Monument preserves the lake bed, along with bats, turtles, early horses and insects.
Wyoming's mammal record includes Uintatherium, a rhino-sized plant eater with six bony knobs on its skull, recorded 24 times from about 51 to 40 million years ago.
Dinosaurs found in Wyoming
The Paleobiology Database lists 938 dinosaur finds in Wyoming. These are the best documented.
- Triceratops: A plant eater with three horns and a bony neck frill. It lived until the extinction 66 million years ago. Found 64 times, from 72.2 to 66 million years ago.
- Allosaurus: A large Late Jurassic predator, 8 to 9 m long, with three-fingered hands and serrated teeth. Found 63 times, from 162 to 143 million years ago.
- Stegosaurus: A plant eater with two rows of upright back plates and four spikes on its tail. Late Jurassic. Found 40 times, from 162 to 143 million years ago.
- Diplodocus: A Late Jurassic long-necked plant eater about 25 m long, with a whip-like tail and peg-shaped teeth. Found 39 times, from 158 to 143 million years ago.
- Apatosaurus: A Late Jurassic long-necked plant eater about 21 m long. Many scientists now treat Brontosaurus as a separate genus. Found 28 times, from 158 to 143 million years ago.
- Tyrannosaurus (T. rex): A meat eater up to 12 m long with a bite strong enough to crush bone. Lived in the Late Cretaceous. Found 15 times, from 72.2 to 66 million years ago.
- Ankylosaurus: A Late Cretaceous plant eater covered in bony armor, with a heavy bone club at the end of its tail. Found 8 times, from 72.2 to 66 million years ago.
- Brachiosaurus: A Late Jurassic plant eater with front legs longer than its hind legs, so its back sloped and its neck rose high. Found 5 times, from 158 to 143 million years ago.
- Acrocanthosaurus: An Early Cretaceous predator about 11 m long with tall spines along its back, among the largest of its time. Found 3 times, from 110 to 93.9 million years ago.
- Camarasaurus: A long-necked plant eater with a short, blunt skull and spoon-shaped teeth. Common in Late Jurassic rock. Found 66 times, from 162 to 143 million years ago.
- Edmontosaurus: A duck-billed dinosaur up to about 12 m long, with hundreds of small teeth packed into its cheeks for grinding plants. Found 25 times, from 72.2 to 66 million years ago.
- Deinonychus: A 3 m predator with a large sickle-shaped claw on each foot. Its 1969 description changed how scientists saw dinosaurs. Found 11 times, from 121 to 93.9 million years ago.
Other fossils found in Wyoming
Beyond dinosaurs, the Wyoming record includes these animals and plants.
- Pteranodon: A toothless flying reptile with a wingspan up to about 6 m and a tall crest. It was not a dinosaur. Found 2 times, from 83.6 to 72.2 million years ago.
- Mammuthus (mammoth): An Ice Age elephant relative with long curved tusks. Woolly mammoths lived in the north, Columbian ones farther south. Found 3 times, from 0.13 to 0.01 million years ago.
- Baculites (baculite): An ammonite with a straight, rod-shaped shell instead of a coil, common in Late Cretaceous seas. Found 149 times, from 93.9 to 66 million years ago.
- Equus (horse): The horse genus, with zebras and donkeys. Horses evolved in North America and died out there in the Ice Age. Found 3 times, from 0.13 to 0.01 million years ago.
- Squalicorax (crow shark): A Late Cretaceous shark with serrated, triangular teeth. Its name means crow shark. Found 16 times, from 93.9 to 72.2 million years ago.
- Elasmosaurus: A Late Cretaceous plesiosaur about 10 m long. Most of its length was neck, with 72 neck bones. Found 1 time, from 83.6 to 72.2 million years ago.
- Uintatherium (uintathere): A rhino-sized Eocene plant eater with six bony knobs on its skull and long upper canines. Found 24 times, from 51.1 to 39.7 million years ago.
- Metasequoia (dawn redwood): Known first as a fossil. Living trees were found in China in the 1940s. Found 79 times, from 66 to 48.1 million years ago.
- Bison: The bison genus. Ice Age bison were larger than today's, and Bison latifrons had horns spanning about 2 m. Found 1 time, from 0.01 to 0 million years ago.
- Hyopsodus: A small, short-legged Eocene mammal, among the most common mammal fossils of its time. Found 826 times, from 57.5 to 39.7 million years ago.
- Sifrhippus (early horse): The earliest known horse, about 5 kg. Its body shrank by about 30 percent as the climate warmed 56 million years ago. Found 442 times, from 56 to 48.1 million years ago.
- Merycoidodon (oreodont): An Oligocene oreodont about 1.4 m long, an extinct plant eater related to camels, not to sheep or pigs. Found 25 times, from 37 to 18.5 million years ago.
State symbols
- State fossil: Knightia (fossil fish) (adopted 1987) Read the statute
- State dinosaur: Triceratops (adopted 1994) Read the statute
W.S. 8-3-112: 'The fossilized fish Knightia is the state fossil of Wyoming' (https://wyoleg.gov/statutes/compress/title08.pdf). SoS page gives adoption date Feb 18 1987. PBDB: Knightia (Clupeidae; Jordan 1907) is valid; a PBDB entry for the name Knightia (Longstaff 1933 gastropod) is a homonym replaced by Knightella - not the fish. | SoS page: Triceratops adopted as State Dinosaur March 18 1994. W.S. 8-3-116 says state dinosaur 'shall be designated by election in accordance with law' with results filed with Secretary of State (https://wyoleg.gov/statutes/compress/title08.pdf), so statute does not name the species. PBDB: valid.
How the land changed
Every fossil records the place it was buried in. Reading those places period by period shows how Wyoming changed.
- Carboniferous (359 to 299 Ma): most fossils from this time come from a shallow sea.
- Permian (299 to 252 Ma): most fossils from this time come from a shallow sea.
- Jurassic (201 to 143 Ma): most fossils from this time come from rivers and lakes.
- Cretaceous (143 to 66 Ma): most fossils from this time come from dry land.
- Paleogene (66 to 23 Ma): most fossils from this time come from dry land.
- Neogene (23 to 2.6 Ma): most fossils from this time come from dry land.
Oldest and youngest finds in Wyoming
The oldest find in the Wyoming record is Glyphaspis, dated to about 505 million years ago. The youngest is Bison, from the last 12,000 years.
Fossil finds in Wyoming by period
| Period | Million years ago | Finds | Most common group |
|---|---|---|---|
| Cambrian | 539 to 487 | 284 | Invertebrates |
| Ordovician | 487 to 443 | 184 | Invertebrates |
| Devonian | 420 to 359 | 147 | Plants and algae |
| Carboniferous | 359 to 299 | 746 | Invertebrates |
| Permian | 299 to 252 | 773 | Invertebrates |
| Triassic | 252 to 201 | 160 | Invertebrates |
| Jurassic | 201 to 143 | 1,382 | Dinosaurs |
| Cretaceous | 143 to 66 | 4,116 | Invertebrates |
| Paleogene | 66 to 23 | 21,207 | Mammals |
| Neogene | 23 to 2.6 | 611 | Mammals |
| Quaternary | 2.6 to 0 | 139 | Reptiles, amphibians and birds |
Frequently asked questions
What is the state fossil of Wyoming?
Wyoming has designated Knightia (fossil fish) as its state fossil, adopted in 1987.
What is the state dinosaur of Wyoming?
Triceratops is the official state dinosaur of Wyoming, adopted in 1994.
What dinosaurs have been found in Wyoming?
The best-documented dinosaurs in the Wyoming record are Triceratops, Allosaurus, Stegosaurus, Diplodocus and Apatosaurus. The Paleobiology Database lists 938 dinosaur finds there.
How many fossils have been found in Wyoming?
The Paleobiology Database records 29,749 fossil finds in Wyoming, covering 2,473 kinds of animals, plants and other life.
What is the oldest fossil found in Wyoming?
The oldest find in the Wyoming record is Glyphaspis, dated to about 505 million years ago.
How can I see fossils near me in Wyoming?
Type a town or ZIP code into the search box at the top of this page, or use your location, to see the fossils recorded within 25 to 200 km. Natural history museums and state fossil parks are the best places to see real specimens.
Keep exploring
More fossil states: California, Texas, Florida, Utah, New Mexico, Montana, all 50 states.
Credits and data
- Fossil finds: the Paleobiology Database, licensed CC BY 4.0. Counts are records in the database, which reflect research effort as well as geology.
- Ancient Earth maps and plate motion: PALEOMAP PaleoDEMs, Scotese and Wright (2018), CC BY 4.0, doi:10.5281/zenodo.5460860.
- Place names: US Census Gazetteer (public domain) and GeoNames, CC BY 4.0.
- Silhouettes: PhyloPic contributors (Jagged Fang Designs, Marie Aimee ALLARD, Olivia Binfield, Scott Hartman, U.S. National Park Service (vectorized by William Gearty), Margot Michaud, David Orr, An Ignorant Atheist, E. D. Cope (modified by T. Michael Keesey, Michael P. Taylor & Matthew J. Wedel), Zimices, Guillaume Dera).