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Discovery of Prehistoric Nests in Alaskan Ice Anticipates Bird Presence in the Arctic by 30 Million Years, Changing the History of Avian Evolution
An international team of scientists made a surprising discovery in the far north of Alaska: fossilized fragments of baby bird bones that lived at least 73 million years ago. These finds, uncovered in the remote Prince Creek Formation, indicate that birds were already nesting in the Arctic during the Late Cretaceous period, much earlier than scientists thought, reports Daily Galaxy.
More than 50 bone fragments, many with characteristic spongy texture of rapidly growing bones, were extracted from extremely fine sediments, under conditions as cold as -30°C. These bones belong to chicks or embryos, suggesting nesting activity at high latitudes, an unexpected behavior for that time.
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During the Late Cretaceous, the Arctic was a milder environment, but still subject to intense seasonal variations. The idea of birds incubating eggs in such a hostile environment, even before the end of the dinosaurs, represents a true paradigm shift for paleontology.
The absence of enantiornithines, a dominant group of archaic birds elsewhere in the world, raises the hypothesis that the birds discovered in the Arctic were closer to modern species — and that they might have had evolutionary advantages to cope with the cold.
These birds coexisted with tyrannosaurs, ceratopsians, and other Arctic dinosaurs. Their coexistence suggests a highly adapted ecosystem, where both dinosaur and bird species were able to reproduce under adverse conditions.
A New Piece in the Puzzle of Bird Evolution
Researcher Lauren Wilson from Princeton University identified three distinct groups among the fossils: birds with teeth resembling those of modern grebes, others resembling gulls, and forms even closer to current birds. This expands the understanding of avian diversity at the end of the Cretaceous.
It is still unclear whether these birds lived year-round in the Arctic or migrated like some species do today. However, the presence of chicks suggests that at least part of the reproduction occurred in the area, something unprecedented for the period.
Paleontologist Steve Brusatte, who did not participate in the study, stated that these birds were already essential parts of polar ecosystems. The discovery reinforces that the ancestors of modern birds played significant ecological roles long before the extinction of the dinosaurs.
The end of the Cretaceous was marked by profound geographic and climatic changes. The Americas were separating, the poles experienced cooling cycles, and biodiversity reached peaks of specialization — including birds, dinosaurs, mammals, and marine reptiles.
This period also preceded the mass extinction that would eliminate non-avian dinosaurs, pterosaurs, and various other species. The survival of modern birds may be linked to this early adaptation to extreme environments, as suggested by the new research.
The discovery not only rewrites part of the evolutionary history of birds but also broadens the understanding of the resilience of the species that survived one of the most drastic events in history.
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