Paleontologists from the University of Colorado Boulder have announced the discovery of a previously unknown mammal fossil near Rangely in northwest Colorado. The mammal, named Heleocola piceanus or “swamp dweller,” lived during the age of the dinosaurs around 70 to 75 million years ago. The identification was made from a jawbone fragment and three molar teeth.
Heleocola piceanus, estimated to have weighed around two pounds and about the size of a muskrat, was a cousin to modern-day marsupials. It likely subsisted on a diet that included plants and a few insects or small animals. “Colorado is a great place to find fossils, but mammals from this time period tend to be pretty rare,” said Jaelyn Eberle, curator of fossil vertebrates and professor at CU Boulder.
“So it’s really neat to see this slice of time preserved in Colorado.”
The region was also home to turtles, duck-billed dinosaurs, and giant crocodiles, which thrived in the marshes and estuaries, feeding on wetland vegetation and fish.
Ancient Colorado mammal discovery explained
Paleontologists John Foster and ReBecca Hunt-Foster, co-authors of the new study, have been excavating fossils in this part of Colorado every summer for about 15 years.
Hunt-Foster described the region’s ancient landscape as resembling modern-day Louisiana, with a variety of water-dwelling animals like sharks and rays. The fossil was collected in 2016 when Foster noticed a fragment of the mammal’s jaw emerging from the sandstone. Measuring about an inch long, the jaw elicited an enthusiastic response.
“I said, ‘Holy cow, that’s huge,'” recalled Foster, who is based in Vernal, Utah. This discovery provides a clearer picture of the diverse and dynamic ecosystems that existed in prehistoric Colorado. It sheds light on a past that would be unrecognizable today, with an inland sea covering much of the American West.
April Isaacs is a news contributor for DevX.com She is long-term, self-proclaimed nerd. She loves all things tech and computers and still has her first Dreamcast system. It is lovingly named Joni, after Joni Mitchell.
