Como Bluff and "The Bone Wars"

An unobtrusive ridge of the Morrison Formation at Como Bluff once contained some of the world’s best-preserved dinosaur bones. Dinosaurs dominated the planet for 165 million years, and many of these large terrestrial species inhabited this region of Wyoming. Como Bluff is a site famous for what was the start of the “bone rush” by fossil collectors. The best view of Como Bluff is from Hwy 30, located about 5 miles east of the town of Medicine Bow, where the western end of the ridge is close to the road. Como Bluff, east of Medicine Bow, Wyoming, was the site of one of the first major discoveries of dinosaur remains in the world. The area received this notoriety because of the sheer number of bones found there and the exceptional preservation of the dinosaur skeletons.

Meet your tour guides, Martin Larsen, (right) geologist with the Wyoming State Geological Survey and Brent Breithaupt, palentologist for the Bureau of Land Management.

Tour guides
Tour guides, Martin Larsen and Brent Breithaupt.

Como Bluff

By Chamois Andersen

The “Age of the Dinosaurs”

Como Bluff is a long ridge with views of sagebrush prairie for as far as the eye can see. It extends roughly east-west, and is about 10 miles long and 1 mile wide. Geologically, the ridge is one limb of an anticline, formed as a result of the Earth compressing and folding, in association with larger geologic events caused by Rocky Mountain plate tectonics. The northern face of Como Bluff shows the outcrops of the Late Jurassic (145-150 million years ago) Morrison Formation. The Jurassic is a period in the Mesozoic Era (66 to 252 million years ago) better known as the “Age of the Dinosaurs.” At the start of the Jurassic Period, the breakup of Pangaea resulted in Laurasia to the north (which broke up into North America and Eurasia) and Gondwana to the south (which broke into Africa and South America). New oceans flooded the landmasses, with mountains rising on the seafloor, pushing sea levels higher onto the continents. All this water created a rather humid climate and lush subtropical environment, supporting a biologically diverse array of plants and animals. Cycads (palm tree-like foliage) covered the landscape, as well as conifers such as Araucaria and pines. The land was home to large terrestrial species, dinosaurs, with many of these predators at the top of the food chain.

Como Bluff and the Bone Wars - WY Cultural Geology

Four types of sauropods were found at Como Bluff. These included the plant-eating Apatosaurus (the correct name for Brontosaurus), Diplodocus, at 90 feet long, Camarasaurus, and Barosaurus. Other large herbivores that inhabited the area during the late Jurassic period included the Stegosaurus (known for its heavy armor), and Camptosaurus, Laosaurus, and Dryosaurus. Carnivores included the Allosaurus, Ceratosaurus, and Ornitholestes.

Many dinosaurs roamed this region we now call Wyoming. Experts say it is a matter of time, place, and climate that prompted dinosaurs to live here. The diversity of plants provided for an abundance of herbivorous, plant-eating dinosaurs. This led to a corresponding abundance of carnivores, the meat-eating dinosaurs. Because so many dinosaur bones were found at Como Bluff, one might consider it the dinosaur capitol of the world, as the dinosaur records show. The discovery of their fossil remains were well preserved in the pastel colored claystones of the Morrison Formation at Como Bluff.

Dinosaur bones collected from the Morrison Formation of southern Wyoming can be viewed at the University of Wyoming Geological Museum in Laramie. The Apatosaurus skeleton in the museum was found in exposures of the Morrison Formation, north of Como Bluff.


Blackstone, D.L., 1971, Traveler’s guide to the geology of Wyoming: Wyoming Geological Survey Bulletin 55, 111 p.

Breithaupt, B.H., 1993, Como Bluff: The dinosaur graveyard: Laramie, University of Wyoming Geological Museum, 1 sheet.

Kohl, M.F., McIntosh, J.S., 1997, Discovering dinosaurs in the old west: The field journals of Arthur Lakes: Washington and London, Smithsonian Institution Press, 198 p.

National Geographic, 2015, Jurassic Period, at, accessed April 6, 2015.

Ostrom, J.H., 1966, Marsh’s dinosaurs: The collections from Como Bluff: New Haven and London, Yale University Press, 388 p.

Como Bluff, The Bone Wars

By Chamois Andersen

The First Fossil Hunters

William Harlow Reed
William Harlow Reed, the first person to discover dinosaur bones at Como Bluff.

 The story of the discovery of dinosaurs at Como Bluff began with two Union Pacific Railroad workers, William Harlow Reed and William Edward Carlin, the section foremen and station agent at Como Station, north of Como Bluff. In July of 1877, Reed found the first dinosaurs at Como Bluff. The two railroad workers turned fossil hunters excavated a “boneyard” of “very thick, well-preserved, and easy to remove” Jurassic fossils at Como Bluff. But two other men also made the history books. The story of the “Bone Wars” is about a bitter rivalry for the area’s dinosaur discoveries, a many years feud between Professor Orthniel Charles Marsh of the Yale University, and Professor Edward Drinker Cope of the Philadelphia Academy of Science.

Historic scene of Como Bluff
Historic scene of Como Bluff, a drawing by Author Lakes.

The Bone Wars

The original diggers, Reed and Carlin, sent some of the bone samples they found to the one of the known fossil experts at the time, O.C. Marsh. To his amazement, Marsh recognized the bones to be of a large sauropod. At the time, Marsh was directing the excavation efforts of dinosaur finds in Colorado. But after seeing the Como Bluff specimens, he immediately instructed his collectors to go to Wyoming. One of these collectors was Prof. Arthur Lakes, who had made other major dinosaur discoveries near Morrison, Colorado. Lakes was a professor at the Colorado School of Mines, and became known for his meticulous paleontology reports and journals with sketches of the outcrops and dinosaur skeletal remains he discovered. He made the journey by rail and immediately joined Reed who showed him the area. Reed became a loyal worker for Professor Marsh. However, Reed’s original digging partner, Carlin, showed his loyalty to Marsh’s archrival Professor Edward Cope. Both professors were well-funded dinosaur hunters with the goal of seeing who could study new dinosaur discoveries. The first to describe a new species had the right to name it. This rush to discovery, and for notoriety in the natural history literature, led to a bitter fight between the two scholars. Although many would say their conduct was not so scholarly, it does make for some good storytelling.

Edward Drinker Cope
Edward Drinker Cope

Charles Darwin

By the 19th century, paleontology (the study of fossils to determine the evolution and interactions of organisms with each other and their environments) had become an emerging natural science. But after Charles Darwin published On the Origin of Species in 1859, the theory of evolution became one of the most controversial subjects of the time. Paleontologist O.C. Marsh became famous for his identification of the Equus parvulus (now Protohippus), the bones of a small horse which many biologists considered proof of Darwin’s theory. In the excerpt below, Darwin expressed his thanks for Marsh’s work in the field.

Aug. 31, 1880

Dear Prof. Marsh,

I received some time ago your very kind note of July 28th, and yesterday the magnificent volume. I have looked with renewed admiration at the plates, and will soon read the text. Your work on these old birds and on the many fossil animals of N. America has afforded the best support to the theory of evolution, which has appeared within the last 20 years.

Sincerely, Charles Darwin

The Dinosaur Rush

Charles O. Marsh
Charles O. Marsh

In 1877, Como Bluff located east of Medicine Bow, Wyoming, was one of the areas that started it all. Dinosaur hunting became the rave in the scientific world, and Como Bluff was at the center of such discoveries and the road to scientific fame. There were large numbers of dinosaur bones found in the Morrison Formation at Como Bluff and most were considered exceptionally preserved. Individual dinosaur bones had been found in England, western Europe, and eastern United States, but not like what was found at Como Bluff. Here complete or nearly complete skeletons were being discovered. Marsh’s crews collected at Como Bluff from 1877 to 1889. During the same time, Cope and his crews also collected there. In such close proximity and while targeting the same dinosaur finds,(all under the direction of the professors), the two divided camps fought hard for their collections, reportedly fist fights, , rock throwing, and even bone smashing. In 1903, most of the major collecting at Como Bluff (including those made by other museums) had occurred. Marsh’s collections resulted in many new species of dinosaur, some with complete or nearly completed skeletons. A well-preserved partial skeleton of what Marsh named as Brontosaurus was found by Reed in 1879. This dinosaur now on display at the Yale Museum in Connecticut is currently referred to as Apatosaurus Thanks to this cast of characters, so focused on digging for fossils at Como Bluff and the story of the Bone Wars, today we have a better understanding of the role of dinosaurs on Earth.

Como Bluff, An Anticline

By Martin Larsen

Within the Morrison Formation of the anticline were well-preserved Dinosaur fossils. Many of the dinosaur bones discovered at Como Bluff were by Palentologist Othniel Charles Marsh and Edward Drinker Cope. With the rush discover and publish – all with fame in mind – a bitter dispute erupted between Marsh and Cope for the quarries, which lead to academic sabotage.

The Como Bluff anticline is a west-plunging, asymmetric fold that extends from the western slopes of the north-trending Laramie Range into the east-central portion of the Laramie Basin. Como Bluff, an anticline with the Morrison formation containing shales and sandstones deposited by rivers about 180 million years ago when dinosaurs roamed the area.

The Como Bluffs axis marks the geomorphic boundary between the Laramie Basin to the south and Shirley Basin to the north. Highway 30 cuts across the plunging nose of the anticline. Formations dating from the Cretaceous, Jurassic, and Triassic periods are exposed in the face of the bluff and in the core of the anticline.

“Como Bluff is an anticline that contains shales and sandstones deposited by rivers about 180 million years ago when dinosaurs roamed the area, ” says Martin Larsen, WSGS geologist.

Como Bluff anticline
Como Bluff anticline, near Medicine Bow, Wyoming [Credit: Chamois Andersen, WSGS, 2015]

The south flank of the anticline is capped with south-dipping Muddy Sandstone and the conglomerate sandstones of the Cloverly Formation. The Cretaceous Cloverly Formation forms a prominent hogback, known as Como Bluff. The Morrison Formation, where a large number of the dinosaur bones were found, is exposed along the northward-facing, steep slope of the ridge. Other formations include the Sundance and Jelm Formations, which are exposed in the lower portions of the ridge, and the Chugwater Formation, which is exposed in the core of the anticline.

The northwest limb of the anticline is bounded by the North Como fault; a high-angle reverse fault. The exposed beds on the north flank are nearly vertical with some beds overturned in places. The resident bed of the Muddy Sandstone forms a northeastward-trending, well defined minor hogback that lies at a lower elevation than Como Ridge.

The low-dipping Jurassic Morrison formation on the south flank of the anticline promoted great excavation opportunities by paleontologists. This-world famous formation consists of shales, thin sandstones, limestone conglomerates, and freshwater limestones. The exposure of this formation has yielded many vertebrate fossil remains. Como Bluff has been called a “dinosaur Graveyard.” In the late 1870s, large numbers of dinosaur bones and well-preserved skeletons were discovered at Como Bluffs.