Fossil Atlas answer
The Morrison Formation is one of North America's classic dinosaur-bearing rock units. It has yielded Stegosaurus, Allosaurus, Diplodocus, Apatosaurus, Brachiosaurus, Camarasaurus, and dozens of other Late Jurassic species, including many of the classic “Bone Wars” dinosaurs that shaped public ideas of the Jurassic.
The formation
The Morrison Formation stretches across a vast swath of the western United States, from Montana to New Mexico. During the Late Jurassic, this region was a broad, low-lying basin with river channels, floodplains, and seasonal lakes bordered by conifer forests and fern prairies. The environment supported enormous herds of long-necked sauropods, armored stegosaurs, theropods like Allosaurus, and a diverse cast of smaller reptiles, mammals, and amphibians.
The Bone Wars
Many Morrison dinosaurs were discovered during the infamous “Bone Wars” of the late 19th century, when rival paleontologists Othniel Charles Marsh and Edward Drinker Cope raced to name new species. Their teams dug quarries at Como Bluff, Wyoming; Garden Park, Colorado; and Dinosaur National Monument, Utah. The competition produced lasting science alongside bitter rivalries and rushed descriptions. Much of what we know about Morrison dinosaurs traces back to Bone Wars discoveries.
Fossil Atlas coverage
The Fossil Atlas Morrison Formation hotspot maps selected fossil records from the current site dataset. Currently, Stegosaurus is the primary Morrison dinosaur with a full profile on the site. As the dataset expands, additional Morrison taxa — including Allosaurus, Diplodocus, and Apatosaurus — may receive individual specimen profiles with mapped records.
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FAQ
The Morrison Formation is one of the classic dinosaur-bearing rock units of western North America. Spread across parts of Colorado, Utah, Wyoming, Montana, New Mexico, and neighboring states, it preserves a Late Jurassic ecosystem of roughly 155–145 million years ago. The formation has produced well-known dinosaurs such as Stegosaurus, Allosaurus, Diplodocus, Apatosaurus, Brachiosaurus, and Camarasaurus. Fossil Atlas currently gives Stegosaurus the strongest linked profile, with the broader Morrison fauna included as formation context.
Different quarries and localities within the Morrison preserve different assemblages. In terms of sheer numbers, Camarasaurus — a medium-sized sauropod — may be the most common dinosaur in the formation, represented by numerous partial skeletons and isolated bones. Among carnivores, Allosaurus is the dominant large predator, with dozens of specimens known from multiple quarries. Stegosaurus, while iconic, is less common than the sauropods, though its distinctive plates and spikes make it immediately recognizable.
The Morrison Formation preserves far more than just dinosaurs. Its fossil record includes crocodilians, turtles, frogs, salamanders, early mammals, pterosaurs, fish, and a rich flora of ferns, cycads, ginkgoes, and conifers. The famous Cleveland-Lloyd Dinosaur Quarry in Utah alone has produced over 12,000 bones from at least 70 individual dinosaurs, dominated by Allosaurus. Trace fossils — footprints and trackways — are also abundant, giving insight into dinosaur movement and behavior.
The Morrison Formation spans the Late Jurassic, from roughly 155 to 145 million years ago (Kimmeridgian to Tithonian stages). This places it about 80–90 million years before the end of the Cretaceous and the extinction of the non-avian dinosaurs. The Morrison was deposited in a semi-arid to seasonally wet environment with river channels, floodplains, and shallow lakes — a landscape that supported enormous sauropod herds and the predators that hunted them.
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Sources
Source links show where Fossil Atlas gets record and curation context. They do not make this page an exhaustive scientific bibliography.
Caveat
The dinosaur list above highlights major Morrison taxa with source-backed records in the current Fossil Atlas dataset. It is not an exhaustive list of every dinosaur known from the Morrison Formation. Additional taxa (Allosaurus, Diplodocus, Apatosaurus) are mentioned for context and may receive individual profiles as the dataset expands.
Fossil maps on linked pages show modern discovery locations for selected records. These are not ancient habitat or range maps.