Here's What Would Happen If Dinosaurs Never Went Extinct

Since the 1800s — when the first dinosaur fossil was discovered for what it was (via Discovery) — humans have been fascinated by the magnificent, alien wonders of our ancient past. Movies like the "Jurassic Park" films captivate audiences and help them imagine what life would be like if humans somehow resurrected these remarkable creatures, but another popular question also arises — what if dinosaurs never went extinct?

In a tragic end, the monstrous lizards were annihilated when an asteroid came hurtling into Earth's atmosphere with the force of 100 million nuclear bombs, according to The Christian Science Monitor. In fact, as the planet faced unprecedented natural disasters, most species living on Earth at the time over the size of 50 pounds, give or take, would've been instantly killed, leaving only 25% of them alive, as BBC shows. But what if the apocalyptic event never happened, and dinosaurs continued to see another day?

In today's world, there are only a few species that descend from the beloved dinosaurs — such as birds, crocodiles, and alligators — but what would've happened if the asteroid missed us or simply hit in a different location? Well, even without a meteor, the dinosaurs might've been facing their own difficult problems.

For one, the planet was undergoing some serious climate change before the asteroid even hit the dinosaurs. Volcanic eruptions in India were leading to global cooling, a drop in sea levels, and altercations to the ecosystem that may have made it challenging for dinosaurs to thrive as they had before, as The Christian Science Monitor points out. Some paleontologists, like Mike Benton, have floated the possibility that dinosaurs might've been going extinct anyways. Benton told BBC, "[Dinosaurs] had just about held their own to the end of the Cretaceous, but we know that mammals were diversifying ... [and] dinosaurs had already been declining for 40 million years." Needless to say, the dinosaurs would've had some of their own challenges ahead of them if they didn't meet such a perilous end.

The dinosaurs may have also had some bad luck on their side, as the meteor that wiped them out hit a pretty vulnerable area. For one, a research paper in 2017 suggests that there was about a 10% chance of the mass extinction that the asteroid caused, and it all has to do with soot. As The Washington Post reports, researchers from Tohoku University, Japan have shown that the amount of soot needed to send the Earth into an Ice Age and cause a mass extinction to the extent that affected the dinosaurs only existed in 13% of Earth's landmass, and the Yucatán peninsula (where the asteroid hit) was part of that.

Other researchers have been doubtful that this soot cloud theory could take credit for the extinction of the dinosaurs alone. It may have been a contributor, but evidence of devastating natural disasters, toxic metal from the asteroid, and the gases that were released most likely also contributed to how 75% of life on Earth went extinct in one day (per The Washington Post). Though many do agree that if the asteroid had hit the ocean just slightly off the peninsula, the Earth's waters might've absorbed much of the impact, and there wouldn't have been such a catastrophic event (via BBC).

Now, imagine a world where the asteroid missed or wasn't as devastating, and climate change wasn't an issue — would dinosaurs live alongside humans? It's an interesting idea, and one that has been explored in pop culture movies like "The Good Dinosaur." But is it likely? In our world today, the extinction of the dinosaurs is what paved the way for mammals to thrive, but in a world where dinosaurs never went extinct, what would've happened? Well, the climate was already changing for a number of reasons, but as The Christian Science Monitor points out, the ginormous rain forests that occupied Earth's continents might've been slowly shrinking to match the changing climate.

Though the enormous size of the dinosaurs made it difficult for mammals to evolve into large animals like elephants, hippos, giraffes, small rodents, and tree-swinging primates might've been able to coexist with the dinosaurs. If climate change continued to shrink plant life and bring to life open grasslands and the aforementioned primates learned to walk on two legs around the new plains, it may be possible that humanoid creatures would've evolved with dinosaurs, Science Focus claims.

If there was an alternative world where humans and dinosaurs lived side-by-side, the result might not be so appealing to the dinosaurs, however. Humans — though not physically large individually — have shown perseverance in surviving with other intimidating species. In fact, humans once occupied the same savannahs as lions, the wintery landscapes that wooly mammoths resided in, along with jaguars, tigers, and other dangerous creatures. If the existence of the wooly mammoths were cut short by primitive humans, maybe dinosaurs would be the ones that would be threatened, not the other way around, according to Science Focus.

Another theory poses that instead of dinosaurs and humans living together, the ancient lizards might've evolved into their own intelligent species. Some researchers believe that smaller dinosaurs might've evolved with the cooling climate and evolved with larger brains that resemble humans, as Gizmodo says. Some species like the troodontids were evolving larger brains, but they weren't believed to be intelligent like primates today or humans, according to Live Science.

Something that is not a matter of debate is that the world would've been a much different place if the dinosaurs, and mostly all other life, had not gone extinct that day, as Science Focus shows. Humans might've not even been here, or the world would've been so entirely different that the entire way of life we know today wouldn't have existed. Whether humans lived with dinosaurs or didn't exist at all, the significance of the day almost all life was destroyed was so impactful that it became a defining part of Earth's history.

However, by continuing to study the extinction of the dinosaurs and how it impacted the world, we can better prepare for natural disasters that may face us in the future and threaten to wipe out humanity, from asteroids to gamma-ray bursts (via Vox). Who knows when the next asteroid will hit, and learning how it has historically affected the planet can help prepare humanity for future events.