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| Newly hatched birds explore a 73-million-year-old Arctic environment. in Wilson, Ksepka, Wilson, Gardner, Erickson, ... et Druckenmiller,. 2025. |
Abstract
Polar ecosystems are structured and enriched by birds, which nest there seasonally and serve as keystone ecosystem members. Despite the ecological importance of polar birds, the origins of high-latitude nesting strategies remain obscured by a sparse fossil record. We report an extreme-latitude Arctic avialan assemblage from the Prince Creek Formation of Alaska—the northernmost Late Cretaceous terrestrial ecosystem. Numerous three-dimensionally preserved fossils constitute one of the most taxonomically rich Late Cretaceous avialan assemblages, including members of Hesperornithes, Ichthyornithes, and near-crown or crown birds (Neornithes), recording a previously undocumented interval in avialan evolution. Abundant perinatal fossils represent the oldest evidence of birds nesting at polar latitudes, which demonstrates that birds began using seasonal polar environments for breeding during the Cretaceous, long before their modern descendants.
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| Newly hatched birds explore a 73-million-year-old Arctic environment. Modern birds breed in the Arctic to take advantage of abundant seasonal resources, but the evolutionary origins of this behavior remain elusive. Exceptional new fossils from northern Alaska reveal birds lived and nested alongside non-avian dinosaurs in Arctic Alaska long before the radiation of modern birds after the end-Cretaceous extinction. Illustration: Gabriel Ugueto |
Lauren N. Wilson, Daniel T. Ksepka, John P. Wilson, Jacob D. Gardner, Gregory M. Erickson, Donald Brinkman, Caleb M. Brown, Jaelyn J. Eberle, Chris L. Organ and Patrick S. Druckenmiller. 2025. Arctic Bird Nesting traces back to the Cretaceous. Science. 388(6750); 974-978. DOI: doi.org/10.1126/science.adt5189 [29 May 2025]
Editor’s summary: In the modern world, birds represent key components of polar ecosystems. This is true even in the face of the extreme seasonal changes that occur in these regions. Although the Cretaceous world was considerably warmer than ours, the polar regions still experienced months of near total darkness, suggesting that this was a challenging environment to colonize even when it didn’t experience extreme cold. Wilson et al. report on a fossil assemblage of birds from the late Cretaceous Arctic. This assemblage includes both chicks and adults of multiple species, suggesting that birds began breeding in Arctic regions early on in their evolution. —Sacha Vignieri