Triops Longicaudatus
Triops Longicaudatus Red
Triops Longicaudatus
Triops Longicaudatus Red
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Palaeontology: Birds lived with dinosaurs in the Arctic
The latest fossil finds prove that birds were already nesting side by side with dinosaurs in the far north 73 million years ago.
The Arctic region is currently one of the most important breeding regions for millions of migratory birds. Every spring, birds return from their wintering grounds. They are attracted by the endless days and the abundance of food. But this spectacular natural spectacle is by no means new, as a recent study shows, the roots of this Arctic habitat for birds go back deep into the Earth’s history.
Astonishing diversity of creatures in the Cretaceous period
An international research team led by Lauren Wilson from Princeton University has discovered fossilised remains in northern Alaska that prove that birds nested in the Arctic at least 73 million years ago. Their findings from the Prince Creek Formation have now been presented in the journal Science and move the presence of birds in the far north a whole 30 million years further back in time than previously documented.
The Prince Creek Formation was home to an astonishing variety of creatures during the late Cretaceous period. These included dinosaurs, as previous finds have shown. This time, the researchers came across around 50 tiny bone fragments. These come from prehistoric birds. They even included the remains of chicks and unhatched embryos. It was a clear indication that these birds not only travelled through the region, but also bred there.
The structure of the bones was particularly revealing. Their porous, not yet fully ossified nature pointed to young animals. The analysis revealed that they were representatives of several bird groups, including the Ichthyornithes, Hesperornithiformes and early representatives of the Neornithes, the group from which today’s birds evolved.
Extreme lighting conditions and climatic fluctuations
The Ichthyornithes resembled modern seagulls or terns in appearance, while the Hesperornithiformes were apparently strongly adapted to life in the water, comparable to today’s alcids or penguins. Both groups still had teeth in their beaks. It was an anatomical feature that modern birds have lost in the course of evolution.
However, the absence of another bird group that was widespread in the Cretaceous period was conspicuous: the Enantiornithes. They also had teeth, but apparently lacked crucial adaptations to survive in the climatic conditions of the Arctic, possibly a reason why they were not represented in the northern latitudes.
Although the climate in the late Cretaceous period was much milder than today and even forests lined the North Pole, there were still months of darkness and probably snow during the polar night. Animals that lived permanently in this region had to be adapted to extreme light conditions and climatic fluctuations. Whether some of the birds migrated south seasonally is still unclear. There is still no clear evidence of migratory behaviour in the Cretaceous period.
With their findings, Wilson’s team not only provides the oldest evidence to date of bird breeding in polar latitudes, but also a fascinating insight into the ecosystem of the late Cretaceous period. They show that the Arctic was already an important habitat for dinosaurs and their feathered descendants at that time.
