Rare dragonfly fossils dating from about 50 million years ago show how life recovered after the mass extinction of the dinosaurs and could benefit our understanding of climate change.
Canadian scientist Bruce Archibald, who examined the fossilized remains of the insects, said the dragonflies would have lived in a period of increasing atmospheric carbon and higher global temperatures.
"These fossil sites in British Columbia and northern Washington provide an unusually clear window into forest ecosystems in a cool upland during a time of hot global climates with high atmospheric carbon.
"There were palm trees at times growing in this temperate upland of British Columbia, in fact, at times growing right up to the Arctic Ocean."
Archibald, a research associate from Simon Fraser University, worked with another dragonfly expert, Robert Cannings, a curator of entomology at Royal BC Museum and they examined nine dragonfly fossils from the McAbee fossil site in Canada's British Columbia and from the town of Republic in northern Washington state in the US. These fossil beds preserve a record of life just over a dozen million years after the extinction of the dinosaurs.
"These dragonflies help fill in the picture of the emerging modern world that we know today when it was experiencing a very different climatic regime: a temperate upland in a warm world with winters so mild as to lack frost days," Archibald said.
"If we want to know where we're headed in the future in a planet with increasing atmospheric carbon and higher global temperatures, it will be good to look to the past," he added.
Archibald said that the fossils would have formed when the dead insects fell into lakes, eventually sinking to the muddy bottom. This mud would be compressed into shale over millions of years.
Dragonfly fossils are rare, he said, because the large wings of dragonflies may have helped them float for a longer time on the water surface before sinking — meaning their chances of being scavenged or of decaying were much greater.
He explained that the fossils came from a period where life and biodiversity were re-emerging following "huge extinctions."
"This is the recovery period. It's the path to the modern world ... it's a period where we are starting to see forests with maple and fir trees — more modern patterns of biodiversity."
The researchers said the fossils represented eight previously unknown species, six of which were well enough preserved to be given scientific names.
The fossils provide insight into how life emerged and developed after the dinosaurs, but crucially for Archibald, comparisons can be drawn with how life functions today.
Unlike other fossilized insects from this era, these dragonflies belong to modern families, mostly to a diverse group called the darners — and would not look out of place today flying beside a modern pond.