Recent findings in the Prince Creek Formation of northern Alaska have uncovered fossilized teeth from three new species of multituberculate mammals, suggesting that the ancient Arctic was a vital environment for mammalian evolution. These species adapted to extreme conditions and migrated between continents, challenging previous notions of Arctic ecosystems during the Late Cretaceous period.

• 01The teeth belong to three newly identified species: Camurodon borealis, Kaniqsiqcosmodon polaris, and Qayaqgruk peregrinus.
• 02Qayaqgruk peregrinus indicates that multituberculates migrated between Asia and North America via a polar land corridor.
• 03The Arctic environment during the Late Cretaceous was characterized by extreme cold, seasonal darkness, and diverse ecosystems, contrary to the idea of it being lifeless.
• 04Multituberculates survived the end-Cretaceous mass extinction, which eliminated around 75% of Earth's species, suggesting their adaptations may have provided advantages in a disrupted world.
• 05The discovery emphasizes the concept of ecological participation over mere geographic presence in defining species' belonging to an environment.

The findings enhance our understanding of the Arctic's ecological history, influencing how we perceive ancient environments and their role in evolution.