Death of the Dinosaurs
by Connie Barlow
Once upon a time, sixty-five million years ago, Earth was in a peak of glory. In fact, for more than a hundred million years Earth had revelled in this state of glory. This was the Age of Dinosaurs. This was the time when Earth embarked on its first celebration of size and ferocity and vigor in land animals.
This was the Mesozoic Era. Sixty-five million years ago was the time when the nimble duck-billed dinosaurs were browsing on marsh plants, and the rhino-like Triceratops was toppling trees. Amazing fossils from this time show the descendants of Velociraptor sitting on nests of carefully arranged eggs. As well, the most formidable predator of all time, Tyrannosaurus rex, was prowling the land.
Meanwhile, in the sea, other kinds of reptiles helped Earth celebrate size and terror. There were the great Plesiosaurs, with their snake-like necks. This is the form that most closely matches reports of the Loch Ness monster in a Scottish lake, reports that titillate us today with the hope that maybe, just maybe, a magical Mesozoic dragon still exists somewhere on Earth. Also swimming in Mesozoic seas were the Ichthyosaurs. Their stream-lined bodies and formidable teeth made them the dolphins of the dinosaur era. Finally, there were the astonishing Mosasaurs, the greatest of whom were the size of lesser whales but had the teeth and gape and terrifying demeanor of a Great White Shark. Earth never before and never since has produced such a formidable monster of the sea. But remember, because all these creatures were reptiles — not fishes — they had to breathe air. So they lived near and regularly roiled the surfaces of all the world's oceans.
We know what happens next. From the standpoint of the dinosaurs and plesiosaurs and ichthyosaurs and mosasaurs, what happens next is disaster. A meteor with the mass of Mount Everest strikes the Caribbean near the Yucatan Peninsula. The collision occurs at such great speed that the force releases a fireball across the planet. Firey debris falls from the sky everywhere. And afterwards, the dust-size particles remain aloft far higher than the tops of the tallest clouds — far higher, therefore, than the sky and the weather might rain them out. The veil of dust blocks the sun over the entire Earth, and winter settles in — settles in unbroken for perhaps three full years.
The darkness and the cold of this cataclysmic winter put a halt to all photosynthesis on land and in the sea. Algae die in the oceans and lakes, all hope for eventual recovery residing in quiescent spores. Land plants that had never before faced a winter die down to their roots, and then the roots die too. Seeds and spores are all that remain, remain in waiting. But for the dinosaurs and the great reptiles of the sea, there are no seeds and spores. There is no life stage that can sit and wait for the passage of three frozen years.
Sycamore trees and pine trees and ferns will make it through the dark time as seed and spore. But dinosaurs and plesiosaurs and ichthyosaurs and mosasaurs will not. From the perspective of Planet Earth, this immense loss of living diversity is indeed a disaster, an outright catastrophe. Sixty-five million years ago, Earth experienced a death with seemingly no prospect for a return to the glory days of size and terror. But rebirth does come, though it takes five to ten million years for this rebirth to fully manifest. Somehow, little mammals made it through the terrible trials of the Dark Time. These ratlike creatures were skilled burrowers during the Age of Dinosaurs. They scurried for cover and came out mostly at night, and so they were accustomed to darkness. They could smell their way to safety and food.
Perhaps these little mammals scavenged for three years on frozen dinosaur bodies: frozen dino dinners. Or perhaps they gathered and ate seeds. Perhaps only a remnant population of mammals made it through in some corner of some continent. But make it through they did. Fifteen million years after the meteor collided with the planet, Earth once again reentered glory days. This was the Age of Mammals. Earth's celebration of size was renewed in the giant brontotheres and ancestral rhinos of fifty million years ago. More, some of the mammals forged partnerships with an utterly new form of plant — a plant that did not exist at all during the Age of Dinosaurs. These were the grasses, and their mammalian partners became wave upon wave of grazers — rhinos, horses, buffalo, antelope. Thirty million years ago, grasses invented a stunning novelty: the ability to grow from the base, rather than the tip. So while other flowering plants on the plains were seriously injured or destroyed by grazing (and now, lawnmowers), the grasses thrived, roots interweaving into a carpet of sod.
Much later, these very same grasses, in the form of barley and wheat and rice, would offer mammals another opportunity for grand invention. This happened just ten thousand years ago; this was the invention of agriculture by one species of bipedal ape. Ten thousand years later, the progeny of these apes would come to discover and celebrate the Great Story of mammals and grasses, the Great Story of the birth and death of dinosaurs, the Great Story of the very origin of the Universe. Ten thousand years later, the progeny of these first farmers would come to sit in this very room, stunned by the memory of the full depth of time and the expanses of space. The death of the dinosaurs would itself lead to a time, sixty-five million years later, when the memory of dinosaurs would be restored and celebrated — in movies, children's fantasies, and our own expansive hearts.
So out of catastrophe, out of a planetary disaster that at the time would have seemed utterly hopeless, would come a renewal, just as winter eventually gives way to spring. After the death of the dinosaurs came a new phase of glory for Earth and living beings. And eventually, an utterly new form of awareness would arise that could for the first time celebrate all that had come and gone before.
_____
CONNIE BARLOW is a science writer and author of The Ghosts of Evolution, Green Space Green Time, and Evolution Extended.