Researchers recently made a rare and important find: thousands of fossilized dinosaur footprints along Alaska’s Yukon River. Dino tracks have been found at other sites in Alaska in the past, but this discovery is significant due to the large concentration of tracks as well as their age.
In July 2013, a team of researchers from the University of Alaska Museum of the North took off by boat down the Yukon River with a plan to stop at beaches along the way to search for signs that dinosaurs once roamed the region. Based in part on ancient rock formations in area, the researchers believed there was potential for evidence of ancient creatures; however, they were uncertain what, if anything, they’d find. As it turned out, the researchers hit the jackpot, discovering an abundance of footprints at every location they checked out. At one beach, they gathered 50 fossils in 10 minutes. “There aren’t many places left in the world where paleontologists can just go out and find thousands of dinosaur footprints. This is the kind of discovery you would have expected in the Lower 48 a hundred years ago,” the museum’s earth sciences curator and one of the trip’s participants, Pat Druckenmiller, said in a statement.
The team found fossilized tracks at the Yukon site from a variety of dinosaur species, both meat-eating and plant-eating. In the past, significant collections of dino tracks have been found along the Colville River in Alaska’s North Slope region, as well as Denali National Park in the state’s interior. The first track in the Denali area was discovered in 2005 and determined to be that of a theropod, a carnivorous creature that lived some 70 million years ago. The tracks at the Yukon site are thought to be 25 million to 30 million years older.
One reason it might’ve taken longer to locate the Yukon footprints than those at previously discovered Alaskan sites is that the Yukon tracks are “natural casts,” meaning they were created when sand filled in the prehistoric animals’ footprints after they clomped in mud. “These are not negative impressions. Rather they stick out from the rock and sometimes look like blobs with toes,” according to Druckenmiller.
The Yukon discovery will help researchers gain a better understanding of the types of dinosaurs that once traipsed around present-day Alaska, as well as the time period in which they did so. Dinosaurs first appeared on the planet some 230 million years ago; they died out about 65 million years ago, for reasons that are not entirely clear. By the early 19th century, humans had become aware that these creatures once existed, and in 1842 British scientist Sir Richard Owen coined the term “Dinosauria,” meaning “terribly great lizards.”
On the 2013 Yukon River expedition, researchers collected some 2,000 pounds of fossils, which were shipped back to Fairbanks for further study. Members of the team plan to return to the Yukon site sometime in the future so they can continue to explore it.