Journey to Alaska

Hadrosaur

Hadrosaur, or duck-billed dinosaur, footprint (cast)

How old is the footprint?
75-65 million years ago (Late Cretaceous)

Where is it from?
Aniakchak National Monument, Alaska

How big were hadrosaurs?
Hadrosaurs were up to 35 feet long and weighed up to 3 ½ tons

What did they eat?
Plants

This is an exact replica of a dinosaur footprint found in 2001 and represents the first record of Cretaceous dinosaurs from western Alaska. The footprint is one of several tracks that are preserved as part of an ancient forest ecosystem. The fossil forest consists of several upright conifer tree trunks, and the leaves of shrubs. Approximately one out of every ten leaves shows damage from plant-eating insects. This ancient ecosystem preserves trees, shrubs, and both large and small plant-eating animals.

Some scientists have speculated that the dinosaurs of the arctic migrated from northern Alaska to more southern latitudes, such as southern Alberta, during the winter months. These workers based their theory of hadrosaur migrations on a well-known migratory animal, the modern caribou. However, a more thorough comparison between hadrosaurs and caribou by staff at this Museum and the University of Alaska Museum suggests that arctic hadrosaurs did not migrate.

Data from different herds of caribou in Alaska showed that juvenile caribou must be roughly 60% adult mass and 85% adult length at the time of migration. Yet analysis of the juvenile hadrosaurs from arctic Alaska showed these young animals had reached only 11% adult mass and 23% adult length, even though the cell structure of their bones indicated that they were more than a year old. These young hadrosaurs were too small to have migrated the 1000s of miles required in the previous model. Therefore we conclude that they stayed in northern Alaska year round.