Fossils of 73 million years provide the oldest proofs of nesting birds at polar latitudes
Polar ecosystems are structured and enriched by birds, which nest in it seasonally and serve as members of the Keystone ecosystem. Despite the ecological importance of polar birds, the origins of high latitude nesting remain obscured by a sparse fossil file. In new research, paleontologists have examined an assembly of bird fossils at the extreme latitude of the formacetace of the upper Cretaceous of Alaska.
An illustration of Cretaceous birds with other dinosaurs from the same period in the background. Image credit: Gabriel Ugueto.
“Birds have existed for 150 million years,” said Lauren Wilson, a doctoral student at Princeton University.
“Since half the time, they have existed, they nest in the Arctic.”
In the study, Wilson and his colleagues analyzed the bones and fossilized teeth of 73 million birds of 73 million birds from the Alaska formation of Prince Creek.
They identified several types of birds – diving birds that looked like humans, birds similar to seagulls and several types of birds similar to modern ducks and geese – which reproduced in the Arctic while the dinosaurs wandered in the same land.
Before this study, the first known evidence of birds reproducing in the Arctic or Antarctica were approximately 47 million years ago, well after an asteroid killed 75% of animals on earth.
“This rejects the bird breeding record in the polar regions of 25 to 30 million years old,” said Dr. Pat Druckenmiller, director of the Alaska University Museum in the North.
“The Arctic is considered to be the nursery for modern birds.”
“Finding bones of Cretaceous birds is already a very rare thing,” said Wilson.
“Finding baby bones is almost unknown. This is why these fossils are important.”
“We put Alaska on the map for fossil birds. It was not on anyone's radar,” added Dr. Druckenmiller.
“We are now one of the best places in the country for bird fossils from the age of dinosaurs.”
“In terms of information content, these small bones and teeth are fascinating and provide an incredible depth of understanding animals of that time.”
It remains to be seen whether these new specimens are the first known members of Neornithes, the group which includes all modern birds.
Some of the new bones only have skeletal characteristics in this group. And, like modern birds, some of these birds did not have real teeth.
“If they are part of the group of modern birds, they would be the oldest fossils ever found,” said Dr. Druckenmiller.
“Currently, the oldest of these fossils are about 69 million years ago.”
“But we had to find a partial or complete skeleton to say it with certainty.”
THE results appear this week in the newspaper Science.
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Lauren N. Wilson et al. 2025. The nesting of the birds of the Arctic traces in the Cretaceous. Science 388 (6750): 974-978; DOI: 10.1126 / Science.Adt5189
