The Most Metal Extinctions in Earth’s History
Extinctions are terrible events that cause death and destruction on a scale our feeble human minds can scarcely comprehend. However limited they may seem to us when we learn about them in school, to witness such an event would certainly be a horrifying experience. From geological cataclysms to cosmic impacts, mass extinctions are bigger and more powerful by far than anything you’ve ever seen. These are the most metal events in history.
I should start, however, with a brief preface — all of these extinctions are shrouded in the mists of time. When we investigate geological data from many millions of years ago, there’s always going to be a degree of uncertainty. Every scenario I discuss, therefore, is simply the one that aligns best with the evidence.
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The Cretaceous-Tertiary Event (65 Million Years Ago)
The Cretaceous extinction is a good jumping-off point for our discussion, as it’s by far the most famous — the one that killed the dinosaurs and replaced them with a bunch of boring mammals. The cause of the End-Cretaceous or Cretaceous-Tertiary extinction was long debated by academics. Some pointed to the fact that volcanism appeared to have increased or that the earth’s atmosphere underwent a steep change in carbon levels. Others suggested that only a massive, sudden, and cataclysmic event could have killed the 75% of animals that disappeared from the fossil record around 65 million years ago.
While even the paleontologists of many decades ago understood that a cosmic impact could have caused a massive die-off, no one had found evidence that such an impact had happened at the correct time. Scientists began to ponder their predicament — surely, such a large-scale trauma to the earth’s surface would leave a mark? Perhaps it landed in the ocean? If it landed in the ocean, would it have caused the same amount of devastation?
Thankfully, geophysicists looking for oil in the 1970s happened upon a certain geological depression in Chicxulub in Mexico’s Yucatan Peninsula. The area was around a hundred kilometers wide, with depressed areas both in and out of the ocean. Though the first scientists didn’t yet recognize the region as an impact crater, a 1990s research team investigated further and discovered shocked quartz, a crystalline structure indicative of extremely high pressures — like those caused by a 10-km-wide asteroid.
What Would It Have Been Like?
For a 10 km asteroid to have made the impact we see today in Chicxulub, scientists estimate, it must have been moving at around 30 km per second. Now, when we see asteroids in movies, they’re often depicted moving at a comically slow pace. This is convenient for filmmakers, as it gives them time to unravel a dramatic plotline, but it’s totally unrealistic. You would not see an asteroid coming.
A .308 bullet used for military and hunting purposes travels at around 800 meters or .8 kilometers per second. This is over 37 times slower than the asteroid that killed the dinosaurs. As it passed through the earth’s atmosphere, it would have created a blinding flash of light. In an instant, another flash of exploding, liquified rock would have turned firm mountainsides into a lethal spray of superheated projectiles rebounding back into the atmosphere and landing hundreds or thousands of kilometers around the impact site.
In Zelda, Majora’s Mask, the moon takes three days to descend to earth but still causes the end of the world
An impact so powerful would have utterly shattered the earth around it. It would have caused widespread earthquakes, flinging hapless tyrannosaurs meters into the air. This ripple effect, like a slow-motion video of a ringing gong, would alone have killed most creatures. Worse, the pressure in the earth’s core would have increased, causing other seismic and volcanic events throughout the globe.
If all of this weren’t enough for the terrified creatures of the earth, the coming hours would have been just as bad. The sky would have turned red and eventually a dark brown. Forests would have caught fire. Pressure winds and sonic events would have inflicted terrible wounds like blast injuries on surviving animals. Tsunamis must have washed aquatic and terrestrial creatures alike off the face of the earth.
For decades after the Chicxulub impact, the soot and dust from the asteroid remained airborne, causing temperatures to drop and light levels to dim. Plants dependent on high light levels died, and animals ill-suited to the cold went extinct. The earth has been around for billions of years, but this is surely one of the worst things to have ever happened to it.
The Permian-Triassic Event (251.9 Million Years Ago)
The Permian-Triassic divide doesn’t get as much press as the End-Cretaceous. Perhaps this is because it happened over 160 million years earlier, but it deserves more attention. The notable thing about this one is that it killed around 96% of life in the oceans and a significant percentage of life on land. Though it happened about 250 million years ago, things would surely be quite different if it had never happened. Perhaps we would be intelligent, talking reptiles instead — who knows?
Permian flora
The Permian period was a strange time for terrestrial life. While life in the seas had long thrived and diversified, life on land had only begun to branch out into its most recognizable forms. Though creatures like large amphibians and reptilian proto mammals wouldn’t have seemed too out-of-place in a modern zoo, they were probably a little clumsier and more lethargic than the animals we see today. Insects were doing great though, and they were going through something of a golden age.
Large, herbivorous parareptiles of the Permian
Reptile-like creatures were abundant, but they weren’t dinosaurs yet. A group called Archosaurs that would give rise to dinosaurs were still more crocodilian than dinosaur-like, but their distinct hip bones would have made their legs face downward like the dinosaurs we know today.
While the Permian-Triassic event was by far the most destructive extinction, it’s among those we know the least about. There are, however, a few strong hypotheses with one clear frontrunner. The most commonly cited ones are deoxygenation (anoxia), asteroid strikes, and volcanism followed by anoxia.
Volcanism, the most popular proposed cause, had to have happened on a massive scale to create such destruction. As continental plates drifted apart, flood basalt, or volcanic flow, would have risen to the earth’s surface in lava tsunamis across thousands of miles, releasing toxic gasses everywhere. Obviously, this would have been bad for just about everything.
What Would It Have Been Like?
Initially, toxic gasses were most concerning for terrestrial creatures. The creatures that weren’t outright vaporized by eruptions would have died from suffocation. Flood basalt usually consists of liquid material, which would have emerged into the earth as plumes of smoke like those seen at Mount Saint Hellens. Just like the asteroid impact that killed the dinosaurs, this would have darkened and reddened the sky, turning the whole world into an abysmal hellscape.
We sometimes think of the ocean as detached from the land areas of the planet, but they suffered most severely from Permian-Triassic eruptions. The water would have heated to insufferable temperatures, and released carbon must have starved the ocean of life-giving oxygen. Microorganisms taking advantage of this increase in carbon would have worsened the problem dramatically.
This event wasn’t as sudden or violent as the one that killed the dinosaurs, but it made life very hard for thousands of years. After the dust settled, the creatures best suited to dominate the land were those who thrived in hot temperatures and whose skin was impermeable by water — proto reptiles and insects, in other words.
The Triassic-Jurassic Mass Extinction (201.3 Million Years Ago)
The Triassic-Jurassic extinction would have been a lot like the one I just described, but it happened over a longer period, and it killed "only" about 50% of living species. Unlike the Permian-Triassic, however, we know a lot more about its effects on terrestrial life. You may recognize that it happened in the middle of the period we associate with dinosaurs, but you may not be aware that it was a defining event that solidified dinosaurs’ place as the undisputed masters of the land for millions of years to come.
Before the Jurassic period, the crocodile-like Archosaurs had diversified into many other groups, some of whom didn’t resemble dinosaurs at all. By the beginning of the Jurassic, most contenders had been starved or suffocated to extinction. Fortunately for mankind, early mammals were another group that handled the extinction well.
What Would It Have Been Like?
Imagine the scenario above, just less bad and with more reptiles running around. This one happened over a long time, but volcanic eruptions are never quite subtle.
The Modern (Anthropocene) Extinction
It’s tough to consider your place in history when you’re still living it. Unfortunately, you may soon find yourself with no other option. Already, humans have wiped out around 60% of mammals. Even a volcanic hellscape never yielded these numbers in such a short time. Though we may still escape extinction ourselves, we’ve earned a permanent place in the list of great extinction causes in the geological record.
Though our methods aren’t quite as grandiose as an asteroid or volcano, there’s something undeniably metal about a bunch of naked apes going around clubbing defenseless birds. In this case, however, the term metal isn’t referring to something so remotely brutal that it’s cool — we’re still very much involved.
While it’s terrible that so many of our favorite creatures and plants face mortal peril, there is an upside — when it’s all over, whatever intelligent beings still inhabit the earth will get to see how everything played out. What dynasty comes next? Walking squid? Giant crabs?
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