A team of paleontologists in Rangely, Colorado, led by Jaelyn Eberle from the University of Colorado Boulder, discovered a new fossil mammal about the size of a muskrat. The fossil, named Heleocola piceanus, lived in Colorado roughly 70 to 75 million years ago during the Age of Dinosaurs. The researchers identified the animal from a jawbone fragment and three molar teeth. This discovery is significant as mammal fossils from this time period are rare in Colorado, and it offers a glimpse into the ecosystems present during the Late Cretaceous.
Compared to the larger dinosaurs that lived at the same time, Heleocola piceanus may seem small, but it was surprisingly large for mammals at that time. Eberle noted that it was a significant find for Colorado, showcasing a slice of time preserved in the state’s fossil record. The discovery sheds light on the diverse fauna that existed in the region when a vast inland sea covered parts of the American West. The name Heleocola roughly translates to “swamp dweller” in Latin, reflecting the animal’s habitat and lifestyle during its time in Colorado.
The discovery of Heleocola piceanus in Rangely adds to the picture of a prehistoric Colorado that would be unfamiliar to current residents. The area was once a place where land met water, hosting a variety of creatures such as turtles, duck-billed dinosaurs, and giant crocodiles. The researchers have been excavating fossils in the region for over 15 years, uncovering evidence of a diverse ecosystem that thrived in marshes and estuaries. The fossils paint a vivid picture of a landscape that resembled regions like Louisiana, with various aquatic species coexisting alongside terrestrial animals.
Before an asteroid caused the extinction of non-avian dinosaurs 66 million years ago, mammals were typically small rodents. They are often identified by the tiny teeth they leave behind in the fossil record. Heleocola piceanus stood out due to its larger size, estimated to weigh over 2 pounds, making it one of the larger mammals from the Late Cretaceous period. This finding challenges previous assumptions about the size of mammals during that time, highlighting the diversity and complexity of ancient ecosystems in Colorado. Despite dinosaurs generally garnering more attention, ancient mammals played a crucial role in shaping the local environment.
The researchers emphasized the importance of preserving fossils found on public lands, urging visitors not to collect vertebrate fossils. Instead, they advise noting the location, taking photographs, and informing nearby museums or public land agencies. Protecting these fossils ensures that scientists from around the world can study and learn from them, contributing to our understanding of prehistoric life in the region. The Mountain West, including areas like Rangely and Dinosaur National Monument, holds a wealth of fossil evidence that sheds light on the history and evolution of life on Earth. The discovery of Heleocola piceanus enriches our knowledge of Colorado’s ancient past and highlights the importance of ongoing paleontological research in the region.