Alaskan Dinosaur Footprints Reveal an Ancient Ecosystem

Friday, November 1, 2019

© iStock/gremlin

The vast number of dinosaur footprints in Alaska reveal that high latitude hadrosaurs preferred tidally influenced habitats, according to the Perot Museum of Nature and Science, Texas.

Dinosaur fossils are common in Alaska, with some of the most famous areas of fossil excavation being Denali National Park and the North Slope. There are very few records of dinosaurs from the Alaskan Peninsula in the southwest part of the state. Anthony Fiorillo and his colleagues from the Perot Museum of Nature and Science in Texas, documented the abundant dinosaur trackways from Aniakchak National Monument, around 670km southwest of Anchorage.

Preserved in the Chignik Formation, the trackways were preserved in a series of coastal sediment deposits dating back to the late Cretaceous Period, around 66m years ago. Survey work from 2001 to 2002 and 2016 to 2018, identified two footprints of armoured dinosaurs, one being from a large predatory tyrannosaur and a few footprints attributable to two types of birds. 93% of the tracks belonged to hadrosaurs, a highly successful herbivore which is typically the most common dinosaurs a high latitude fossil ecosystem.

The researchers explained: “While there are now numerous records of dinosaurs from Cretaceous rocks around the state of Alaska, very few fossil records of terrestrial vertebrates are known from the Mesozoic rocks of the southwestern part of the state. Here we report the new discovery of extensive occurrences of dinosaur tracks from Aniakchak National Monument of the Alaska Peninsula.”

Previous research conducted in northern Alaska has found that hadrosaurs were more abundant in coastal habitats. The trackway documented revealed that the same trend was apparent in southern Alaska. The authors of the study suggest that understanding habitat preferences of dinosaurs will contribute to the understanding of how ecosystems change through time as environmental conditions shifted and dinosaurs migrated across northern corridors between continents.

Fiorillo adds, “Our study shows us something about habitat preferences for some dinosaurs and also that duck-billed dinosaurs were incredibly abundant. Duck-billed dinosaurs were as commonplace as cows, though given we are working in Alaska, perhaps it is better to consider them the caribou of the Cretaceous.”