Was it the day they spilled a milkshake all over themselves while talking to a girl they liked in a McDonalds? Was it the day they spent hours walking around in public while not knowing there was a giant hole in the rear of their pants? Though I wasn’t around for the 66,000,000,000 or so days when dinosaurs dominated the Earth, if I were to hazard a guess, I would say the worst day the dinosaurs ever had was the day about 66 million years ago when a giant object from outer space smashed into the Earth, because that was the day that likely caused a whole lot of dinosaur species to go extinct.
This giant object from outer space was an asteroid that was at least six miles wide. Just having a six-mile-wide rock laid gently on top of you would ruin your day, but this asteroid came flying in from space traveling at least 45,000 miles per hour by the time it smashed into the Gulf of Mexico. The impact released enough destructive energy to equal a million hydrogen bombs. The force of it created an impact crater that was (and still is) 110 miles wide (it’s called the Chicxulub Crater).
So, if you happened to be a mosasaur directly under this plummeting giant object as it whacked the Gulf of Mexico (mosasaurs were marine reptiles that lived at that time, though they weren’t dinosaurs) that would have been a particularly bad day. But even for dinosaurs on land on the other side of the world, the asteroid impact was the beginning of a series of bad days. The asteroid was traveling northwest, so when it hit the Gulf of Mexico, most of the energy and chunks of rocks from the impact went toward northern Mexico, the United States and Canada, meaning every triceratops or other large dinosaurs from Chihuahua, Mexico to Walla Walla, Washington (and a much larger area than that) may have been wiped out by the explosive forces as quickly as you can delete the word “triceratops” on a Word document (though it might have taken a couple minutes for the explosive forces to reach Walla Walla and then the deleting would happen).
The impacting asteroid also had so much force that it set-off huge, mega-tsunamis around the Gulf of Mexico, and shook the entire planet enough to likely trigger earthquakes and volcanic eruptions around the world.
This day is already way worse than, say, a day when you wet your pants in a shopping mall, but the dinosaurs’ bad day doesn’t end there. Some of the tiny chunks of rocks and dust that were kicked up to the stratosphere by the impact were eventually pulled back down by gravity and then they heated up as the fell through the atmosphere (like Superman or the Space Shuttle do whenever they return from space). It would have looked kind of like this 2015 NASA photo of space junk falling to earth and heating up, except these fireballs would have been everywhere:
There were so many of these superheated bits of rock raining down, that the atmosphere around the planet heated up to the point where you could have baked cookies in it. It was also enough heat to possibly set-off forest fires around the world.
Not all the bits of rocks from the impact fell down to Earth, though. Some of the tiniest dust was able to float in the atmosphere for years, along with dust from any volcanic eruptions that were set-off by the impact. There was enough dust in the air after the impact to block out the sun for months to years and plunge the Earth into a winter that lasted for as long as the atmospheric dust blocked the sunlight. Without sun, any plants that survived the day of the impact would have died during the long winter. Without plants, the animals would quickly run-out of food and more of them would start dying too.
As horrible as all of that is, it is still not the end of everything that happened because of that one bad day. All that dust in the air caused yet another disaster. Most of that dust came from the rocks in the Gulf of Mexico seafloor that were shattered by the asteroid impact. These rocks and rock dust had a lot of sulfur in them. The sulfur in the dust in the air eventually mixed with rain to create sulfuric acid rain that rained down on the oceans for years, helping to kill off a lot of marine life, particularly all the sea creatures that had shells.
We are not 100% sure all of this happened the way I described it, but there is evidence for all of it and that either some combination of these disasters, or possibly all of them, worked together to wipe out not just all the non-avian dinosaurs, but possibly 75% of the species on Earth, everything from plants to plankton. Basically, as far as we can tell, just about everything on Earth bigger than a chicken died at that time.
Also, not all scientists agree the asteroid impact was the thing that wiped out most of the dinosaurs. A few scientists think it was more likely prolonged climate change that caused most dinosaur species to go extinct. A few others think it was prolonged volcanic activity, particularly volcanic activity by a supervolcano called the Deccan Traps that was located in what today is India. And, of course, cartoonist Gary Larson had the best explanation ever for what caused this mass extinction event:
But the vast majority of scientists are in agreement that the asteroid impact was the culprit.
So this has been the most depressing post I’ve ever written, but the good news is the next time you feel bad because you think that your hair looks weird at school, be thankful that a bad hair day is not as bad as having a giant asteroid hit the gym.
The other good news related to this post is that I was actually able to fly to the Gulf of Mexico to join, for a few days, the scientific expedition to drill into the Chicxulub Crater. The scientists participating in this expedition are hoping to learn more about the impact of the dinosaur-killing asteroid. You can learn more about this expedition here.
To learn more about how we know what happened after that giant object from outer space stuck the Earth, read my book Uncovering Earth's Secrets.
And, yes, all those non-impact-crater-related bad days described above happened to me.
Online References and Resources:
ECORD Science Operator. "Expedition 364-Chicxulub K-Pg Impact Crater"
LiveScience. "Asteroid Impact That Killed the Dinosaurs: New Evidence"
Lunar and Planetary Institute. "Global Effects of the Chicxulub Impact Event."
Photos and Images:
Click the photos and images used above to find their sources.