A team of researchers from the University of Alaska Fairbanks (UAF) has made an amazing discovery at Denali National Park and Preserve, the largest dinosaur footprint site in Alaska. Covering an area equivalent to one and a half soccer fields, this amazing site, dubbed the “Coliseum” by scientists, provides a glimpse of the diverse species of dinosaurs that lived in interior Alaska some 70 million years ago. This groundbreaking find sheds new light on the prehistoric world and provides valuable insights into the ancient environment.
Sequence in time
Lead author Dustin Stewart, who conducted this study while a graduate student in paleontology at UAF, explains that the “Colosseum” is not just one level of rock with footprints, but rather a sequence in time. This sets it apart from previously known footprint sites in Denali, making it truly unique. Stewart states, “There have been other known sites on Denali so far, but nothing like this.”
At first glance, it may appear that the Coliseum is just another rocky outcropping amidst the vast topography of Denali National Park. However, upon closer inspection, the significance of the site becomes apparent. Senior study author Pat Druckenmiller, curator of the University of Alaska Museum of the North, explains that a first visit to the site yielded little. But as dusk descended and sunlight fell on the rocks, the footprints came to life. Druckenmiller recalls this moment, “When the sun lays perfectly on these strata, they just exploded. We were all just blown away.”
A look at the Late Cretaceous Period
The rocks that form the Colosseum were once layers of sedimentary rock near a common watering place on a vast floodplain during the Late Cretaceous period, about 100.5 to 66 million years ago. Over time, tectonic movements shifted these flat layers and stood upright, exposing footprints. Footprints found at this site include fossilized footprints from ancient times and casts formed after sedimentary rocks filled the depressions and hardened. Druckenmiller calls the footprints “beautiful,” emphasizing the intricate details that show the shape of the toes and the texture of the skin.
Keys to the ancient environment
In addition to the dinosaur footprints, there have been other remarkable finds at the Colosseum. Fossils of ancient plants, preserved pollen, and evidence of freshwater mollusks and invertebrates have been discovered. These small finds provide valuable information for reconstructing the environment during that period. Stewart explains that these finds help paint a picture of what the region looked like thousands of years ago: tall coniferous and deciduous trees, dense undergrowth of ferns and horsetails, and a climate similar to today’s Pacific Northwest.
Tracks found at Colosseum indicate that the region was home to a wide variety of dinosaurs, both juvenile and adult, for thousands of years. While the most common were herbivorous duck-billed and horned dinosaurs, there were also evidence of predators, tyrannosaurs and water birds. This indicates a diverse ecosystem teeming with life during the Late Cretaceous in Interior Alaska.
The discovery of Alaska’s largest dinosaur footprint site at Coliseum is a milestone in paleontological research. It provides a unique opportunity to study the ancient world and gain insight into prehistoric habitats. By continuing to analyze and study the footprints and associated fossils, scientists hope to uncover more secrets about the dinosaurs that once roamed Alaska’s interior.