Erosion caused by heavy rains uncovered an
BOULDER, Colo. – Paleontologists have announced their discovery of an ancient mammal that lived around 70-75 million years ago in a swampy area of what is today northwestern Colorado.
In a study published this week, the scientists identified the animal as Heleocola piceanus, a creature about the size of a muskrat living at the time dinosaurs roamed the Earth.
The name is inspired by the environment where the creature lived. Unlike the Colorado known today, the Colorado of H. piceanus’s time was partially underwater.
Artist’s depiction of H. piceanus in a Late Cretaceous swamp. (Illustration by Brian Engh-LivingRelicProductions.com, courtesy of Utah Field House of Natural History)
(Brian Engh / FOX Weather)
“The region might have looked kind of like Louisiana,” said ReBecca Hunt-Foster, co-author on the study and a paleontologist at Dinosaur National Monument in Utah and western Colorado. “We see a lot of animals that were living in the water quite happily, like sharks, rays and guitarfish.”
DINOSAUR FOSSIL REVEALED AFTER HEAVY RAINS IN BRAZIL
Because of this swampy environment, the newly identified mammal’s name roughly means “swamp dweller” in Latin, according to the University of Colorado.
Map of a body of water known as the Western Interior Seaway covering much of North America roughly 75 million years ago.
(Sampson et al., 2010, PLOS ONE / FOX Weather)
Weighing 2 pounds or more, H. piceanus would have been large compared to other mammals of its time, according to lead author and professor in the Department of Geological Sciences Jaelyn Eberle. She noted the animal is a cousin to today’s marsupials.
Eberle and her team made their discovery by analyzing fossils found in the Williams Fork Formation in Rangely, Colorado, in the mid-to late 1980s, along with fossils they found in the same area in the 2000s.
3D scans of the fossil jawbone of the mammal H. piceanus.
(Eberle et al, 2024, PLOS ONE / FOX Weather)
The earlier fossils were originally thought to belong to other ancient mammal species, Aquiladelphis incus and Glasbius piceanus.
However, further research, along with analysis of fossils discovered in 2018, upended this classification and led scientists to the conclusion that they had identified a new species of ancient mammal in Colorado.
“Colorado is a great place to find fossils, but mammals from this time period tend to be pretty rare,” Eberle said. “So it’s really neat to see this slice of time preserved in Colorado.”