Duck-Billed Dinosaur Footprints, Made Nearly 70 Million Years Ago, Discovered In Alaska

A team of researchers, studying fossils of pre-historic animals, has discovered a new site in Alaska’s Denali National Park, which is filled with a huge number of footprints believed to have been made by duck-billed dinosaurs, or “hadrosaurs,” in the prehistoric Arctic.

The new discovery suggests that the hadrosaurs not only roamed in herds but also flourished in the ancient high-latitude, polar ecosystem. The findings also provide new insights into the herd structure and evolutionary history of dinosaurs at the North Pole, the scientists said in a study, recently published in the journal Geology.

“Denali is one of the best dinosaur footprint localities in the world. What we found that last day was incredible -- so many tracks, so big and well preserved,” Anthony R. Fiorillo, a curator at the Perot Museum of Nature and Science in Dallas, Texas, and the study’s lead author, said in a statement.

“Many had skin impressions, so we could see what the bottom of their feet looked like. There were many invertebrate traces -- imprints of bugs, worms, larvae and more -- which were important because they showed an ecosystem existed during the warm parts of the years,” he said.

The researchers could identify four distinct sizes of footprints, ranging from 5 inches to 24 inches. While more than 80 percent of the tracks were believed to have been made by adults, 13 percent of the tracks likely belonged to young hadrosaurs and only 3 percent were believed to have come from juvenile hadrosaurs, Live Science reported.

Based on the small number of juvenile footprints, the researchers have concluded that the young hadrosaurs might have spent only a short period of time being small and vulnerable. The tracks also helped the researchers to theorize that the juveniles were probably unable to migrate to other places, so the hadrosaurs spent their entire lives in the Arctic.

Fiorillo and his team of researchers have been studying the new Denali track site since 2011, and believe that the tracks were likely made between 72 million years to 69 million years ago in a muddy river during the summer.

“If you take a great big herd of plains eaters, they have to move at some level, otherwise they strip out all the vegetation,” Live Science quoted Fiorillo as saying. “But there's a growing data set that suggests they didn't do the thousand and thousands of miles of migration that was originally considered.”