Jurassic National Monument facts for kids

Quick facts for kids Jurassic National Monument
Cleveland-Lloyd Dinosaur Quarry Visitor Center
Jurassic National Monument Location in Utah
Location	Emery County, Utah
Nearest city	Cleveland
Governing body	Bureau of Land Management
U.S. National Natural Landmark
Designated:	1965

A skull of Allosaurus fragilis, found here and now in a museum in Germany.

The landscape of Jurassic National Monument in 2019.

The Jurassic National Monument is a special place in Utah where many dinosaur fossils have been found. It's also known as the Cleveland-Lloyd Dinosaur Quarry. This site has the most dinosaur fossils from the Jurassic period ever discovered in one spot. It's located near Cleveland, Utah, in an area called the San Rafael Swell. The fossils are found in a type of rock layer known as the Morrison Formation.

More than 15,000 dinosaur bones have been dug up here. There are still many more bones waiting to be found and studied. In 1965, this site was named a National Natural Landmark. This means it's a very important natural area. In 2019, it officially became a national monument.

Scientists have found bones from many different dinosaur species all mixed together. The bones are also "disarticulated," meaning they are not connected like a full skeleton. One idea is that this place was a "predator trap." This means animals got stuck in soft mud, and then other predators came to eat them and got stuck too. However, scientists are still debating this idea today.

Visiting the Monument

The Bureau of Land Management runs the visitor center at the monument. Inside, you can see a reconstructed skeleton of an adult Allosaurus. There are also many other bones and exhibits to explore. The visitor center was updated and expanded in 2007. It's open during certain seasons, so check their hours before you go.

A Look Back: History of the Quarry

Sheepherders and cattlemen first found the quarry in the late 1800s. They were moving their animals through the area. In 1927, scientists from the University of Utah visited and collected about 800 bones.

From 1939 to 1941, a team from Princeton University came to dig for fossils. This team was led by William Lee Stokes, who is known as the "Father of Utah geology." The site was named Cleveland-Lloyd Quarry because it was near Cleveland, Utah, and Malcolm Lloyd helped pay for the expeditions. In three summers, the Princeton team collected 1,200 bones.

Some of these bones were sent to Princeton, New Jersey. They were used to build a complete Allosaurus skeleton. This skeleton was finally put on display in 1961. It was likely the first Allosaurus skeleton built from bones found at this quarry.

After World War II, digging started again in 1960. A young paleontologist named James Henry Madsen Jr. joined the University of Utah to help with the excavations.

In 1960, Stokes and Madsen started the "University of Utah Cooperative Dinosaur Project." This project helped museums and other places around the world get dinosaur casts or real specimens. In return, these places helped with money and digging. The project ended in 1976. Madsen then started his own company, Dinolab, to sell dinosaur casts.

New dinosaurs were also discovered here! In 1974, Madsen described a new dinosaur. He named it Stokesosaurus clevelandi to honor his mentor, William Lee Stokes. In 1976, another new dinosaur was found. Madsen named it Marshosaurus bicentesimus after an American paleontologist named Othniel Charles Marsh. In 1987, scientists from Brigham Young University found a fossilized dinosaur egg. At the time, it was the oldest dinosaur egg ever discovered!

Over the years, more than 12,000 fossil bones have been collected from the quarry. Most of the original fossils are kept at the Natural History Museum of Utah. But many dinosaur skeletons made from Cleveland-Lloyd remains are on display in over 65 museums worldwide. You can see original fossils in Utah at the Natural History Museum of Utah in Salt Lake City, the USU Eastern Prehistoric Museum in Price, and the Earth Science Museum at Brigham Young University in Provo.

The Bureau of Land Management (BLM) opened a visitor center at the quarry in 1968. This was the first visitor center ever opened by the BLM! A new, larger center with updated exhibits opened in 2007. This new center even makes its own electricity using solar panels on the roof.

In early 2019, the quarry officially became the "Jurassic National Monument."

Why So Many Dinosaurs? The Geology of the Quarry

The Cleveland-Lloyd Dinosaur Quarry is famous for having so many dinosaur bones. It's part of a rock layer called the Brushy Basin Member of the Morrison Formation. Scientists think this area might have been a "predator trap."

Imagine a muddy pond on a floodplain. This pond was in a low area between natural dirt walls (levees) of a river system. The mud in the pond was sticky and thick. Dinosaurs might have gotten stuck in this mud when they came to drink or hunt.

Most of the fossils found here are from meat-eating dinosaurs. About 67% of all the bones are from Allosaurus (at least 44 individuals!). Other meat-eaters include Torvosaurus, Ceratosaurus, Stokesosaurus, Marshosaurus, and possibly Ornitholestes.

Plant-eating dinosaurs found here include Camarasaurus, Haplocanthosaurus, Barosaurus, Amphicoelias, Mongolosaurus, Camptosaurus, and Stegosaurus. There are also fossils of a crocodile, turtles, snails, and ancient plants.

It's unusual to find so many meat-eating dinosaurs compared to plant-eaters (about 3 meat-eaters for every 1 plant-eater). One idea is that Allosaurus hunted in packs. Smaller Allosaurus might have worked together to catch prey. They might have followed their prey into the muddy pond and then gotten stuck themselves. Larger meat-eaters probably got stuck while trying to eat the trapped dinosaurs.

However, some scientists have a different idea. They think the dinosaurs died during a severe drought. Dinosaurs might have come to the area looking for water. They could have died from the harsh conditions or from diseases caused by drinking dirty water. This theory is supported by the fact that many of the Allosaurus specimens are young dinosaurs. Scientists are still studying the evidence and debating what really happened!

Ancient Life: Paleofauna Found Here

Many different types of ancient life have been found at the Cleveland-Lloyd site.

Plants

• Aclistochara
• Latochara
• Stellatochara

Snails and Shells

• Amplovalvata
• Amplovoluta
• Valvata
• Viviparus

Turtles

• Glyptops

Dinosaurs

Ornithischians (Bird-Hipped Dinosaurs)

Bird-Hipped Dinosaurs Found at Cleveland-Lloyd Quarry
Genus	Species	Notes	Images
Camptosaurus	C. dispar		Stegosaurus
Stegosaurus	S. stenops	This was the largest bird-hipped dinosaur found here.

Sauropods (Long-Necked Dinosaurs)

Long-Necked Dinosaurs Found at Cleveland-Lloyd Quarry
Genus	Species	Notes	Images
Apatosaurus	A. sp		Apatosaurus Camarasaurus
Barosaurus	B. sp
Camarasaurus	C. lentus	Three skeletons of this dinosaur were found.

Theropods (Meat-Eating Dinosaurs)

Meat-Eating Dinosaurs Found at Cleveland-Lloyd Quarry
Genus	Species	Amount	Notes	Images
Allosaurus	A. fragilis	44 - 60	This was the largest meat-eating dinosaur found at the quarry.	A mounted skeleton of Allosaurus Tanycolagreus
Ceratosaurus	C. nasicornis	1	This is the rarest meat-eating dinosaur found here.
Marshosaurus	M. bicentesimus	2
Stokesosaurus	S. clevelandi	3	This was the largest "coelurosaur" (a type of meat-eating dinosaur) found here.
Tanycolagreus	T. topwilsoni	1	Its remains were first thought to be Stokesosaurus clevelandi.

Images for kids

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  Exhibit buildings and visitor center at Jurassic National Monument.

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  A map showing the thousands of dinosaur bones found at the Cleveland-Lloyd Dinosaur Quarry.