The dinosaurs are not all dead.
I saw one raise its iron head
To watch me walking down the road
Beyond our house today.
Its jaws were dripping with a load
Of earth and grass that it had cropped.
It must have heard me where I stopped,
Snorted white steam my way,
And stretched its long neck out to see,
And chewed, and grinned quite amiably.
by Charles Malam
Cute little poem, eh? I thought of it when this piece of heavy equipment appeared in the field next-door. It was used to tidy up the erosion that had eaten away at the drainage ditches along the edges of the corn field. Cute, but not true, of course. Outside of heavy equipment, you’re not going to see any dinosaurs wandering about these days.
Six great spasms of extinction have struck the planet over the last 500 million years. The dinosaurs disappeared about 65 million years ago, when some apocalyptic shock rocked the planet. Maybe a massive meteorite crashed into the earth at 72,000 kilometers an hour. Or maybe huge volcanic eruptions filled the sky with ash. Or maybe the meteorite strike set off volcanoes. Whatever it was, this event is known as the K-T boundary, the end of the Cretaceous period (the youngest period of the Mesozoic era) and the Tertiary period, the oldest of the Cenozoic era. It’s easy to imagine this giant rock falling from space and boom, the dinosaurs all keel over dead. Not quite. The extinctions of various groups were spread out over millions of years on either side of the K-T boundary. Dinosaurs died out over about 10 million years.
Dinosaurs used to be, probably still are, a popular subject with primary students. As a parent, I got very tired of dinosaurs as each child progressed through dinosaur units at school. I’m pretty sure teachers loved dinosaurs not because they hoped to turn out a generation of paleontologists, but because they found dinosaurs helpful in leading their restless XYers into basic literacy. In any case, most kindergarteners could identify stegosaurus or triceratops and even discuss the merits of the volcano or meteorite theory. Unfortunately, fewer youngsters could tell you that the K-T boundary represented the 5th Great Extinction. Nor could they tell you much about the 6th Great Extinction, its timeline, or its cause. The 6th Great Extinction is ongoing. We are the cause.
The 6th Great Extinction began centuries ago, as humans spread around the globe. In Madagascar, humans arrived about 500 AD. Following hard on their arrival was the extinction of the elephant birds, birds like the Aepyornis maximus, a giant almost 10 feet tall, with massive legs. Seven of the seventeen genera of lemurs disappeared. A pygmy hippopotamus, two huge species of land tortoises, an aardvark, all gone. In New Zealand, the Moa, another giant bird disappeared. The Thylacine, the largest marsupial predator to have survived into historic times, was exterminated from Tasmania. The Dodo was infamously slaughtered on Mauritius. In recent times, unfathomable numbers of passenger pigeons were destroyed. Of course, that’s just a tiny list of notables, some of the megafauna, from a long, long list of extinctions. E.O. Wilson estimates 27,000 species are currently lost per year. Scientist Paul Ehrlich estimates extinction rates at 7,000 to 13,000 times the background rate, 70,000 to 130,000 species per year. By 2022, 22% of all species will be extinct if no action is taken. As the human population spirals beyond the carrying capacity of the planet, habitat loss is the most significant cause of extinctions. If we fail to arrest climate change, the rate of extinctions we are already causing will increase.