From the Bay of Fundy's sedimentary cliffs to the Rocky Mountain shale, and from the Niagara Escarpment to the Arctic, Canadian dig sites have turned up evidence for every major development in Earth’s evolutionary drama
Author of the article: Joseph Brean
Publishing date: Nov 30, 2021 •
Curator Jean-Bernard Caron says the Royal Ontario Museum wants visitors to its new Dawn of Life exhibit to “realize how long it took to get to where we are today.”
PHOTO BY PETER J. THOMPSON/NATIONAL POST
The oldest fossil evidence of life on Earth was discovered a few years ago on Inuit land near Inukjuak on Hudson Bay in northern Quebec, a special place where the planet’s oldest crust is exposed at the surface.
The oldest fossil evidence of life on Earth was discovered a few years ago on Inuit land near Inukjuak on Hudson Bay in northern Quebec, a special place where the planet’s oldest crust is exposed at the surface.
In a week’s time, visitors to a unique new museum exhibit will be invited not only to behold this archaic life form, but to touch a cross section of this scientifically invaluable rock, to make a physical connection with another organism across four billion years, to feel the rough minerality, and to understand that the microscopic tube and filament structures within these bands of iron were put there by a living thing as it clustered around hot vents in the ancient ocean floor.
Like the other pieces in this exhibit on life’s earliest manifestations, the Inukjuak fossil shows how Canada’s geography structures the story of life’s evolution on Earth, and not just because there are dinosaurs in the Alberta Badlands. From the sedimentary cliffs of the Bay of Fundy to the Rocky Mountain shale, and from the Niagara Escarpment to the Arctic, Canadian dig sites have turned up evidence for every major development in this planet’s evolutionary drama, including fish moving onto land, vertebrates laying eggs, four-limbed bodies, and entire animals growing into fractal symmetries.
Seeing these wonders of science in the flesh, or at least in the rock and artistic models, depends on just one remaining uncertainty. They still need to wrap up construction. It is a mess in there. After three years of planning and disruption, the building of the Willner Madge Gallery, Dawn of Life at the Royal Ontario Museum in Toronto is going down to the wire, just like your typical bathroom reno.
Power tools shriek and workers dart between packing crates as Jean-Bernard Caron, curator of invertebrate paleontology, offers a tour. He says it is the only such exhibit in North America, and a major play by the ROM to showcase its world-leading fossil collection from the Burgess Shale in British Columbia, which preserved the earliest soft tissues from the Cambrian explosion when animals first appeared more than 500 million years ago.
Never mind the dinosaurs, not even half as old as that. This is the story of life growing up, back in the day. Caron calls it a unique opportunity to address a forgotten four billion years.
“We want people to realize how long it took to get to where we are today,” he said.
There is, for example, a display on LUCA, the last universal common ancestor of every creature on Earth today, thought to have lived as far back in time as the oldest known fossil. Caron calls it “an organism to which we all belong.”
The reason for that belonging, that life on Earth is a single family, resists breezy summary. But let’s try. Before four billion years ago, Earth was a hellscape. It is literally called the Hadean period. A smaller planet called Theia smashed into proto-Earth, knocked it off its axis, which is why there are seasons, and splashed up debris that became the Moon, which is why there are tides. Asteroids bombarded the entire solar system and impacted Earth in vast cataclysms for hundreds of millions of years. But then it all settled down, and round about this time, life appeared, apparently as soon as physically possible, almost certainly in water, and probably around hot vents like the Inukjuak microbes. Like a lit fuse, life continued to burn down the millennia, sparking explosion after explosion of new creatures, some which were luckily buried and fossilized in stone, often in land that became Canada. Now they are here, behind freshly Windexed glass.
“We are not telling the story of the origin of life,” Caron said. The gallery takes the existence of life for granted, and invites visitors to join the story in media res, as life grows organically through fits and starts into an epic genealogical tree.
“Life predates the first fossil,” Caron said, and fossils are the main attraction here, starting with the Inukjuak sample that is dated to as many as 4.2 billion years ago.
Inukjuak is not the only major Canadian site in the history of life. Canada’s geography gives structure to this story that begins with archaic single-celled life and progresses through all the complex rest that followed over billions of years of random mutation and natural selection.
From Mistaken Point on Newfoundland’s Avalon Peninsula, there are fossils of creatures called rangeomorphs from 541 million years ago, whose entire bodies are fractal symmetries, unlike anything alive today, but comparable, in their self-similar patterns of decreasing size, to human lungs. Behind glass, they are presented as colourful models recreated by artists alongside the actual fossils. One looks like a goblet, another like an ice cream cone, another like an urn made of feathers.
From the cliffs at Joggins, NS, on the Bay of Fundy, where vast ancient ferns grew so big the sediments buried them vertically, there is evidence of the first amniotic eggs in vertebrates, which enabled creatures to venture further from water to lay eggs on land.
From Miguasha on the Gulf of St. Lawrence in Quebec, there is evidence of the earliest four-limbed body structure in a 375 million year old lobe-finned fish called Elpistostege watsoni, which marks the transition of aquatic creatures to life on land around 360 million years ago. Other fossils show the earliest evidence of bilaterality, or two-sidedness, and even of movement.
The gallery is a tour of Canada, but Caron also conceives of it as a time ribbon, progressing north from the museum’s rotunda and looping through a video installation before reaching Bloor Street four billion years later, where the exhibit ends a mere 200 million years ago, barely a chapter in the book of life. From there, a set of doors opens to the ROM’s famous collection of those much younger creatures that so dominate the prehistoric imagination, the dinosaurs.
“The biggest chunk of time is in this gallery,” Caron said, beside an unfinished display of rock formations called stromatolites from Great Slave Lake in the Northwest Territories and Thunder Bay on Lake Superior in Ontario. “Within three metres you have three billion years.”
These rocks were built by photosynthetic bacteria that built up in layers or mats in shallow water. For anything living at this time, the oxygen these bacteria produced was toxic. One evolutionary response was that cells became bigger with separate parts to deal with oxygen. Simple cells combined with other simple cells to form more complex ones. “They changed the trajectory of life,” Caron said.
The tree of life does not keep growing inevitably, of course. Sometimes it sheds entire branches in mass extinction events, often an ice age, when sea levels drop and creatures in shallow water die out. The amazing thing about these cataclysms, Caron points out, is what comes next. The best example is his research specialty, the Cambrian explosion of countless new life forms, the best fossil evidence for which comes from the Burgess Shale in Yoho National Park in British Columbia. The museum has a quarter million specimens from this Rocky Mountain site, of which the finest are on display here, including a fish ancestor of all modern vertebrates.
The star of the show is a life-sized model of Anomalocaris Canadensis, literally “strange Canadian shrimp,” a ferocious predator as big as a dog with two face claws and a mouth ringed all around with teeth.
“She’s smiling at me,” Caron said. “We are face to face with our own ancestors.”
Sure enough, they are as wondrous and weird as any human family.
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