Type
Federal Quarry / National Natural Landmark
Age
Late Jurassic (Morrison Formation), ~150 mya
Established
Excavations began 1920s–1930s
Best time
April through October when the monument road is open and dry
- ◆Over 12,000 bones excavated from a small area
- ◆At least 46 individual Allosaurus — a predator-dominated bonebed
- ◆Source of Utah's state fossil, Allosaurus
- ◆Active visitor center inside the Jurassic National Monument
Photos
Overview
The Cleveland-Lloyd Dinosaur Quarry holds the densest concentration of Jurassic dinosaur bones ever found — more than 12,000 bones packed into a small area. Strangely, the assemblage is dominated by the meat-eater Allosaurus rather than the plant-eaters that usually outnumber predators, making the site a long-running scientific mystery often described as a 'predator trap.'
Geology
The bones lie in the Morrison Formation. One leading idea is that the spot was a boggy, mud-rich death trap: plant-eaters became mired, attracted predators, and those predators in turn became stuck, concentrating Allosaurus bones over time. Other models invoke a drought-stricken watering hole. The unusual bone chemistry and jumbled preservation keep the debate alive.
What You See
A visitor center and two enclosed quarry buildings let you see bones still in the ground, along with displays explaining the predator-trap hypothesis. The site sits within the Jurassic National Monument, managed by the Bureau of Land Management.
Famous Finds
More than 46 individual Allosaurus have been identified here, which is why Allosaurus is Utah's state fossil. Stegosaurus, Camarasaurus, Ceratosaurus, and other Morrison animals are also represented, but the predator dominance is the site's signature.
Visiting
The quarry is remote, reached by gravel roads south of Price, Utah — check conditions and hours before driving out. The enclosed quarry buildings and interpretive center reward the trip for serious dinosaur enthusiasts.
Best time to visit
April through October when the monument road is open and dry. Avoid monsoon-season mud on gravel roads. Mid-week visits are quietest.
Getting there
From Price, Utah: 32 miles south on paved and gravel roads (SR-10, then Elgin/Clawson road). High-clearance recommended after storms. No services at the site — fill up in Price.
Map
Emery County, Utah — approximate location only. Exact fossil localities are not published to protect sites from looting.
Market & Provenance
Allosaurus material sold commercially often references Morrison Formation provenance — legitimate specimens must come from private land, never from this BLM monument.
Collecting & Legality
Collecting is prohibited. This is federal land managed by the BLM as a National Natural Landmark; removing fossils is illegal. Legitimate Morrison material on the market comes only from private-land quarries with documentation.
FAQ
Why so many Allosaurus?
The 'predator trap' hypothesis suggests animals became mired in mud, attracting more predators — but scientists still debate the exact cause.
Is it part of a national park?
It is Jurassic National Monument, managed by the BLM — not NPS, but still federally protected.
Can I collect here?
No. All fossils on BLM monument land are protected.