Researchers have discovered the earliest evidence known to science of birds nesting in the Arctic.  A newly published study in the journal “Science” indicates that birds were nesting in polar regions during the Late Cretaceous.  Ancient Arctic birds nested alongside dinosaurs.  Fossils collected from the famous Prince Creek Formation of Alaska push back the record of Arctic nesting birds by up to thirty million years.

An illustration of Cretaceous Period birds with other dinosaurs from the same time period in the background. A paper in the journal Science documents the earliest-known example of birds nesting in the polar regions. A dromaeosaur feeds whilst Pachyrhinosaurus congregate in the background. Picture credit: Gabriel Ugueto.

Picture credit: Gabriel Ugueto

Ancient Arctic Birds

The University of Alaska Fairbanks led the research team.  However, researchers from the University of Reading were involved.  The scientists identified dozens of tiny fossil bones and teeth from the Alaskan excavation site.  Multiple types of birds were breeding in the Arctic. For example, diving birds that resembled loons, gull-like birds, and several kinds of birds similar to modern ducks and geese.  Analysis of the structure of the fossil material demonstrated that the bones represented very young birds such as hatchlings.

A hatchling bird beak, top left, and three foot bones are pictured to scale on a penny. The bones’ spongy texture tells scientists that they come from hatchlings, rather than adult birds. Picture credit: Pat Druckenmiller.

Picture credit: Pat Druckenmiller

The sediments are approximately seventy-three million years old (late Campanian faunal stage of the Cretaceous).

To read a blog post about dinosaurs nesting in the Arctic: Dinosaurs Nested in the Arctic.

Lead author of the study, Lauren Wilson, a doctoral student at Princeton University commented:

“Birds have existed for 150 million years. For half of the time they have existed, they have been nesting in the Arctic. Finding bird bones from the Cretaceous is already very rare. To find baby bird bones is almost unheard of. That is why these fossils are significant.”

More than Fifty Bird Fossils Found

Birds are key components in modern polar ecosystems.  Many species breed in these regions and spend all year either in the Arctic or Antarctic.  Although the Cretaceous polar regions were much warmer than today, they were still extreme, harsh environments.  Cretaceous polar regions would have experienced months of near total darkness.  They were challenging environments to colonise even though they were not as cold as they are today.  The fossil assemblage from the Prince Creek Formation suggests that chicks and adults of multiple species lived in the Arctic.  This suggests that birds began breeding in the Arctic early on in their evolution.

Prior to this research, the earliest known evidence of birds breeding in the polar regions dates to approximately forty-seven million years ago.  This was during the Eocene Epoch. The fossil material used in this study was collected from Prince Creek Formation exposures along the Colville River. Rather than focusing on large bones, the scientists collected every bone and tooth they could find from screen washes. Screen washing involves taking tubs of sediment and screening the sediments using sieves.  Once the majority of the stones and pebbles have been removed the remaining material is examined under a microscope.  In this way, tiny fossils including those of hatchling birds can be identified.

Joe Keeney, Patrick Druckenmiller and Jim Baichtal excavate at a site on the Colville River. Picture credit: Lauren Wilson.

Picture credit: Lauren Wilson

Evidence of Neornithes

Some of the tiny bones have skeletal features only found in Neornithes, the group that includes all extant birds. Like extant birds, some of these ancient species had no true teeth.

Co-author of the study, Dr Jacob Gardner (University of Reading) commented:

“Determining the identity of fossils using separate individual bones is notoriously difficult. For the first time, we determined the identities of large numbers of fossils using high-resolution scans and the latest computer tools, revealing an enormous diversity of birds in this ancient Arctic ecosystem. Polar bird communities have deeper evolutionary roots than previously imagined.”

Everything Dinosaur acknowledges the assistance of a media release from the University of Reading in the compilation of this article.

The scientific paper: “Arctic bird nesting traces back to the Cretaceous” by Wilson, L. N., Ksepka, D. T., Wilson, J. P., Gardner, J. D., Erickson, G. M., Brinkman, D., Brown, C. M., Eberle, J. J., Organ, C. L. and Druckenmiller, P. S. published in the journal Science.

For models and replicas of prehistoric animals: Dinosaur and Prehistoric Animal Models.