Fossil Atlas answer
Stegosaurus fossils come from the Late Jurassic Morrison Formation of the western United States — especially Colorado, Utah, and Wyoming. First discovered during the Bone Wars of the 1870s, Stegosaurus remains one of the most recognizable dinosaurs, with its distinctive plates and tail spikes.
Primary location
The Morrison Formation is the core Stegosaurus formation represented on Fossil Atlas. Deposited during the Late Jurassic, it records a semi-arid landscape of river channels, floodplains, and seasonal lakes. Stegosaurus shared this world with sauropods, theropods such as Allosaurus, and a broader cast of smaller reptiles and mammals.
Discovery history
When Othniel Charles Marsh first described Stegosaurus, he misunderstood the plates as lying flat on the back like shingles on a roof — hence the name, 'roofed lizard.' It was only later, with the discovery of articulated specimens, that paleontologists understood the plates stood upright in alternating rows. The tail spikes, or thagomizer, were also initially misidentified until a specimen was found with spikes in place at the tail tip. Stegosaurus became a centerpiece of the Bone Wars narrative, one of Marsh's most celebrated (if initially misunderstood) discoveries.
Fossil Atlas coverage
The Fossil Atlas Stegosaurus profile maps selected occurrence records from the current site dataset. The Morrison Formation hotspot currently includes Stegosaurus as a notable animal, with mapped records showing selected modern fossil localities. As the dataset expands, additional Morrison taxa may receive individual specimen profiles.
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FAQ
The first Stegosaurus fossils were discovered in 1877 near Morrison, Colorado — the town that gives the Morrison Formation its name. The find was made during the height of the Bone Wars, the bitter rivalry between Othniel Charles Marsh and Edward Drinker Cope. Marsh named Stegosaurus armatus in 1877 based on fragmentary material. Over the following years, more complete specimens from Como Bluff, Wyoming, and Garden Park, Colorado, gave Marsh a clearer picture of the animal, though he initially misinterpreted the plates as lying flat like roof shingles — hence the name 'roofed lizard.'
Stegosaurus is almost exclusively found in the Morrison Formation, a Late Jurassic rock unit exposed across the western United States — Colorado, Utah, Wyoming, Montana, and New Mexico. Known quarry sites include Como Bluff (Wyoming), Garden Park (Colorado), Dinosaur National Monument (Utah/Colorado), and the Cleveland-Lloyd Dinosaur Quarry (Utah). A small number of fragmentary stegosaur fossils from Portugal and possibly other European localities were once attributed to Stegosaurus but are now generally considered distinct genera (Miragaia, Dacentrurus).
Stegosaurus is known from a smaller sample than animals like Triceratops, and many specimens are incomplete. Complete articulated skeletons are rare. Named specimens such as Sophie are useful examples of why completeness matters, but Fossil Atlas does not try to rank every specimen. The site focuses on selected records, formation context, and modern discovery locations.
Yes, though less frequently than the abundant Hell Creek dinosaurs. Morrison Formation outcrops continue to yield new Stegosaurus material, especially in the classic quarry regions of Wyoming and Colorado. Because Morrison exposures are spread across millions of acres of federal and private land, new sites are discovered periodically. Advances in preparation and CT scanning also mean that existing museum specimens continue to yield new data decades after collection.
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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 formation list above highlights the main Stegosaurus context used by Fossil Atlas. Fragmentary stegosaur material from outside North America has a complex taxonomic history, so this page avoids treating those records as simple Stegosaurus map points.
Fossil maps on linked pages show modern discovery locations for selected records. These are not ancient habitat or range maps.