6 Extinct Animals That Inhabited Colorado

6 Extinct Animals That Inhabited Colorado

Colorado has changed dramatically over recent geological eras. A report by CU Boulder even suggests that 500 million years ago Colorado had a coastal environment, which made it an ideal place for a variety of different species to flourish.

Today, Colorado remains known for its incredible array of species, but here are a few you might not have known once called the home of the Centennial State.

1. Stegosaurus







Stegosaurus in the swamp

Photo credit: CoreyFord. File photo. (Stock)




Paleontologists believe that stegosaurs roamed the Centennial State around 155 million years ago.

Stegosaurus were a Jurassic species estimated to have been around 30 feet long and 15 feet tall.

The dinosaur is easily distinguished by the plates along its back. In fact, the word stegosaurus translates to “bony plates” in Greek, however, there is some debate regarding the purpose of the plates.

“One theory is that the plates contained blood vessels, to help regulate body temperature. Another idea is that the plates were used to attract mates, like colored feathers on a bird or antlers on a deer,” said said the National Park Service in a statement. post on their website.

Stegosaurus thrived so well in Colorado that it was named a state dinosaur in 1982.

2. Former camel







Camelops was a camel-like herbivorous animal that lived in North America during the Pleistocene period.  Image credit: CoreyFord (iStock).

Camelops was a camel-like herbivorous animal that lived in North America during the Pleistocene period. Image credit: CoreyFord (iStock).




Ancient camels, or camelops, likely made Colorado their home 2.6 million years ago. Scientists estimate they were about seven feet tall at the shoulder and weighed around 1,800 pounds.

“Like living camels, Camelops had two-toed hoofed feet and a long neck. At present, paleontologists are unable to determine whether Camelops had a hump on its back like live Bactrian and Dromedary camels,” according to NPS.

In 2021, Colorado Department of Transportation crews discovered Camelops fossils while working on the construction site of the “Central 70 Project”.







The camelops hesternus molar fossil.  Photo credit: Kiewit Infrastructure Co.

The camelops hesternus molar fossil. Photo credit: Kiewit Infrastructure Co.


3. Tyrannosaurus Rex







T-Rex skeleton.  Photo credit: LG-Photography (iStock).

T-Rex skeleton. Photo credit: LG-Photography (iStock).




Fossil evidence suggests that at some point during the Cretaceous Period, there was Tyrannosaurus Rex in Colorado. In fact, the very first T-Rex teeth were discovered in Golden, Colorado in 1874.

Tyrannosaurus Rex literally translates to “King of the Tyrant Lizards”, which is an apt name for one of the most ferocious beasts in history.

Scientists believe the T-Rex was around 38 feet long and could weigh up to 10 tons. They had powerful jaws, a keen sense of smell, and were one of the top predators of the time.

4. Ornithomimus







Ornithomimus figures

Photo credit: Savany. File photo. (Stock)




Ornithomimus fossils were first discovered in 1889 in Denver. They lived during the Late Cretaceous period and are considered to be one of the fastest dinosaurs that ever existed. They stood about six feet tall and were about ten feet long from snout to tail.

Ornithomimus means “bird imitator” in Greek, which refers to their similarities to the modern ostrich.

5. Giant Ground Sloth (Megalonyx)







Megalonyx research tree

Photo credit: Aunt_Spray. File photo. (Stock)




Giant ground sloths roamed the earth around 35 million years ago, during the Pleistocene era. These massive mammals were estimated to be around 10 feet long and weighed around 2,200 pounds, according to NPS.

Fossils of giant ground sloths were first found in 1797 in West Virginia, and were discovered later at the Ziegler Reservoir site near Snowmass Village, Colorado.

“Like other ground sloths, the greater clawed sloth was slow-moving and most likely lived alone. Like other ground sloths, Megalonyx likely used its large size and claws to deter predators,” NPS said.

6. American Cheetah







Alert cheetah Photo credit: WLDavies (iStock).

Photo credit: WLDavies (iStock).




Sometimes referred to as a “false cheetah”, the American cheetah is not really related to the animal that roams the world today, it was just extremely similar.

With a build similar to the modern cheetah, the American cheetah is believed to be the reason the Colorado remains the second fastest mammal on the planet – the pronghorn.

Complete skeletal remains of this animal have been found on the continent, with fossils discovered in Colorado.

This animal roamed the region during the Pleistocene era, around 12,000 years ago.

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