B.C. fossil beds show insects’ emergence
Simon Fraser University scientist Bruce Archibald struggled for decades to persuade the provincial government it should protect fossil beds near Cache Creek from commercial developments that included a proposal they be quarried for cat litter.
The government finally listened and designated it a heritage site. Insect specimens excavated from the McAbee Shales confirm the accuracy of Archibald’s case in a groundbreaking new study that pushes back the time at which ancient species began to differentiate into modern species now essential to agriculture and food production at a time both appear threatened by climate change.
The specimens, preserved in the sediments of an ancient lake bed, are providing the international science community with a stunning window into ecosystems that flourished across what is now British Columbia at a key transition point in global climate change 50 million years ago.
“We can see how our modern world emerged after the extinction of the dinosaurs by looking at the change in insect communities at that time,” Archibald said. “Fossil sites extending across southern B.C. into northern Washington provide an unusually clear view into how the world began to become modern after the extinction of the dinosaurs — how a change in insect life was a revolutionary change toward modern terrestrial ecosystems.
“We get a clear view of an ecological revolution that did a lot to create our modern world.”
The end of the Eocene, about 35 million years ago, was a time of abrupt climate change. Theories of what triggered the change include a sudden increase in volcanic eruptions, a series of large meteorite strikes — one of which left a crater 100 kilometres in diameter — and large-scale changes in ocean currents.
But the period is also of great interest because the end of the Eocene was marked by a mass extinction event. One of the largest mammals to exist — Basilosaurus, an ancient eel-like whale with a head like a crocodile — was among of the more notable victims. So were species ranging from large camel-like mammals to marine mollusks.
Archibald was working as a longshoreman when his interest in fossilized insects sent him on a long journey to a PhD in paleoentomology and work not only at SFU but with the Museum of Comparative Zoology at Harvard University and with the Royal British Columbia Museum.
He excavated at the McAbee site and, on the basis of what he found, began arguing tirelessly (and to the profound irritation of some) that it would turn out to be one of the most important paleontological sites in Canada — or anywhere else, for that matter.
The most recent study, based on specimens from McAbee and from eight other sites scattered across what is known as the Okanagan Highlands, a geological region that sprawls from near Smithers to the northern interior of Washington state, is evidence of his foresight.
It dramatically expands scientific knowledge of a crucial evolutionary transition from the Eocene, which began 56 million years ago, to the present Holocene.
The research, just published in the science journal Canadian Entomologist with Archibald as one of the lead scientists, shows that diversification of ancient insect species into those readily familiar in the modern world began far earlier than previously thought.
An international team of scientists from Russia, Africa and Canada examined and compared specimens of ants, bees, wasps and sawflies — categorized as the insect order Hymenoptera because of their membraned wings — from the eight fossil sites in B.C. and one just across the border in Washington.
In B.C., sites beside McAbee included Driftwood Canyon in the north, Horsefly River in the Cariboo, Hat Creek near Cache Creek, Tranquille and Falkland near Kamloops, Quilchena near Merritt, the Allenby formation near Princeton, and a site at Republic, Wash.
The sites preserve a detailed record of the animals and plants inhabiting a vast region characterized by forests, lakes and swamps during a warmer, wetter climate between the end of the age of dinosaurs and the emergence of the modern world we know.
It was during this period that saw the evolution of insects essential to sustaining the global ecosystems upon which humans now rely. Bees, for example, are crucial in pollination and propagation of critical food crops, while wasps are vital in assisting farmers by controlling many pest species that attack those crops.
“Ants, bees and their relatives play an essential role in forming and maintaining the character of modern terrestrial ecosystems,” Archibald said. “We can understand better how this happened by looking and the rich and unique 50-million-year-old fossils of B.C.”