The Late Cretaceous period was 100.5-66 million years ago during a time when the Earth was dominated by dinosaurs. Living alongside these giant reptiles, however, were a variety of different types of mammals.

Up until recently, it was believed that these mammals were all quite small, about the size of a mouse on the large end. They would live in the underbrush, working to avoid dinosaurs and eat plants as well as any scraps of meat they could find.

A new study that was published in the journal PLoS ONE, however, shows that there was at least one mammal that was significantly larger.

The study looked at fossils that were found in Colorado, revealing a brand new species of animal not previously known to exist. It has been named Helocola Piceanus. Helocola in Latin roughly means “swamp dweller.”

This might be a weird name since Colorado today is not at all swampy, but millions of years ago it was. The region was dominated by large lakes and other freshwater features.

They found remains of a jawbone along with three molar teeth. The study suggests that this animal was likely an omnivore, with the bulk of its diet being made up of plants but also consuming insects and smaller vertebrates.

What really stands out about this find is its size. It is much larger than any mammals previously known to live during that time period. While it would be impossible to give an exact size based just on the fossils that were found, scientists suggest it would be about the size of a modern muskrat.

Anytime a new animal is discovered it is an exciting event, and when the animal changes the entire way that experts look at the time period in which it lived, it is even more important. This is just one more reason why it is so important that people keep looking for fossils that can help people to learn more about life on Earth millions of years ago.

Prehistoric Earth may have been much different than we thought.

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