While it’s no secret that the Centennial State is home to plenty of locations where dinosaur fossils have been found, there are some that are unique to Colorado – including one that was once thought to be proof of “sea monsters,” and many more.

Here are some dinosaur species that have been found in Colorado:

1. Theiophytalia kerri

In 1878, James H. Kerr found the remnants of a species of dinosaur that has only ever been found in Colorado Springs’ Garden of the Gods. Although Kerr originally thought that the discovery was a mix of “21 different sea monsters,” it was later announced that the fossil was a newly discovered species estimated to be about 125 million years old, and it’s the only fossil representation of the species in the world.

According to Westside Pioneer, the species is believed to be a herbivore in the Cretaceous period, about 30 feet long and weighing around three tons. The visitor center at Garden of the Gods features an exhibit about the Theiophytalia kerri, which features a realistic model of the dinosaur and a replica of the skull that was discovered.

2. Fruitadens haagarorum

Believed to have lived about 150 million years ago, this dinosaur’s remnants were reportedly found in the 1970s in the Morrison Formation near Fruita according to the Smithsonian Magazine. The dinosaur weighs less than two pounds and measures only 28 inches long.

3. Tyrannosaurus rex

The first Tyrannosaurus rex tooth was found by Arthur Lakes in 18754 on South Table Mountain in Golden. However, the T. rex was not formally recognized and named until a partial skeleton was found in Montana in 1905.

4. Triceratops

The first discovery of a Triceratops remnant was to be published was made near what is now north Federal Boulevard in Denver. According to Dinosaur Ridge, two large horns were reportedly misidentified as bison horns.

5. Stegosaurus

According to Uncover Colorado, the first Stegosaurus fossil found in the world was discovered in Colorado in 1876, outside the town of Morrison. The Stegosaurus was named Colorado’s official state fossil in `1982 by Governor Richard SD. Lamm.

6. Diplodocus

Uncover Colorado says that the Diplodocus was first discovered in Canon City in 1877 by S.W. Williston. Uncover Colorado also notes that the dinosaur was estimated to be about 95 feet, although some even argue that it could be closed to 115 feet.

7. Allosaurus

This large carnivorous dinosaur was reportedly found in Granby by sheepherders. According to Uncover Colorado, they originally thought they had found a petrified horse hoof, but research revealed that it was the fossilized vertebra of the Allosaurus.

8. Apatosaurus

This dinosaur species was also discovered by Arthur Lakes in the Morrison Formation in 1877. Uncover Colorado says that the apatosaurus weighed up to 49,000 pounds and stood up to 75 feet tall.

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