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13 Things That Could Happen If Dinosaurs Were Still Alive

How different would our world be if "terrible lizards" were still among us?

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Sharp-shinned hawk portrait taken during Fall bird migrations at Hawk Ridge Bird Observatory in Duluth, Minnesota
natmac stock/Shutterstock

Well, for starters, they are

That’s right, dinosaurs do still exist, and they are everywhere—in the form of birds. That adorable little sparrow on your windowsill? Dinosaur. The noisy blue jay disturbing your morning coffee? Dinosaur. Pigeons, geese, hawks, you name it—they’re all descendants of large, two-legged, non-avian dinosaurs called theropods. Theropods, “whose members include the towering Tyrannosaurus rex and the smaller velociraptors,” according to Scientific American, adapted certain existing dino features (like feathers) into the birds we see today. Dinosaur extinction is just one myth scientists wish people would unlearn.

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We wouldn’t have recognized them

Say that species-extinction asteroid hadn’t hit Mexico 66 million years ago and life on Earth had continued apace. Well-known dinosaurs like the Triceratops “would be totally different than anything we know from the fossil record,” science writer Brian Switek wrote in The Guardian. Why? They, too, would have continued to adapt. “There might even be new groups of dinosaurs that didn’t exist during the Mesozoic era. The present Earth wouldn’t be a hodgepodge of old favorites, but an entirely different mix of unknown dinosaurs,” wrote Switek. But even extinct dinosaurs looked nothing like what most people believed when they were kids.

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Tyrannosaurus rex skull.Close up of Giant Dinosaur : T-rex skeleton

In fact, we might never have seen them at all

Why? It’s likely that, with a preponderance of dinosaurs remaining on our planet, humans and many other mammals would not have had the chance to evolve into existence. “Even though mammals thrived in the shadow of the dinosaurs, they did so at small size,” writes Switek. “And even though the very first primates had evolved by the end of the dinosaurian reign, they had more in common with a tree shrew than with you or me…[dinosaurs] would have undoubtedly continued to influence mammalian evolution.”

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jurassic park

It would not look like Jurassic Park

The movie took a lot of liberties with the possible, wrote biologist Ben Waggoner in Forbes. “Dilophosaurus, the critter that spit poison in Wayne Knight’s face, lived about 120 million years and 6000 miles away from Velociraptor, the critters that ate Bob Peck. So if all the extinct dinosaurs suddenly started roaming the Earth together at the same time … well, you’d have utter ecological chaos, as the Velociraptors discovered that their tactics for hunting Protoceratops were ineffective against unfamiliar Ankylosaurus, and Triceratops found out that it had no idea how to dodge Allosaurus.” As much as we love it, Jurassic Park makes our list of the most scientifically inaccurate movies.

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Part of the chaos? Dead herbivores

Plant eaters like Edmontosaurus, snacking on the rich diversity of flowering plants that exist today on and in our plains, prairies, and forests, would likely have gotten sick and perhaps even died from this diet. At the very least, wrote Waggoner, they might have just spent their whole lives hallucinating. The chemical makeup of modern plants isn’t anything like what dinosaur biology was meant to handle. Other, more palatable plants might have been completely decimated by the hungry (and huge) critters. Check out these frightening ancient animals you’ll be glad are extinct.

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Fossil skeleton of Dinosaur king Tyrannosaurus Rex ( t-rex ) on wooden base and blackboard background retro vintage style and copy space.
Ton Bangkeaw/Shutterstock

Happy times for carnivores!

All those dead and dying herbivores lying around—poisoned by flowering grasses and other plants their systems couldn’t handle—would have presented a total feeding bonanza for Tyrannosaurus rex, for example, and other at-least-partial scavengers, according to Forbes. Easy pickings! If you love dinos, these are the world’s best dinosaur museums.

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Real dinosaur footprint , Thailand.

But that bounty would have been short-lived

That’s because the dead animals would run out eventually. And when that happened, what would T. rex and friends eat then? “There were mammals alive at the same time and place as T. rex, but none very big—and for all we know, modern mammal flesh might be unpalatable,” wrote Waggoner. Also likely: “A T. rex that was lucky enough to find a turkey farm would probably eat the birds like so much popcorn.”

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Tropical green leaves background, fern, palm and Monstera Deliciosa leaf on wall with dark toning, floral jungle pattern concept background, close up

Climate change would have mixed things up

“An event known as the Paleocene-Eocene Thermal Maximum, 55 million years ago, saw average global temperatures reach 8 [degrees] C hotter than today, and rainforests spanning much of the planet,” according to BBC Future. “In this hothouse world with abundant vegetation, perhaps many long-necked sauropods might have grown more rapidly, breeding at a younger age and shrinking in size; several ‘dwarf’ sauropods (some little bigger than a cow) were already known from European islands in the late Cretaceous.” Learn the exact difference between climate change and global warming.

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Taxus baccata closeup. Conifer needles and fruits. Green branches of yew tree with red berries (Taxus baccata, English yew, European yew). Green coniferous.
Peter Kniez/Shutterstock

So would fruit

Many modern birds have adapted to eating fruit and drinking the nectar of our numerous flowering plants—in fact, these things co-evolved so that birds would disperse the plants’ seeds. Some non-bird vegetarian dinosaurs could have developed this ability as well. Some or all may have grown into gradually smaller animals thanks to the relative ease of digestion of fruits and flowering plants compared to the gymnosperms of the Cretaceous, paleontologist Matt Bonnan told BBC Future. Dinosaurs aren’t the only thing to have gone extinct—here are 14 facts about animals that have gone the way of the dodo in the past 100 years.

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Grasslands 1
Brian C. Weed/Shutterstock

Adapting to grasslands

In the absence of dinosaurs, mammals evolved—slowly—to have the ability to eat grassland plants. Vertebrate paleontologist Darren Naish speculated that surviving dinosaurs would have evolved much quicker thanks to evolutionary advantages they’d already developed, like the “batteries” of up to 1,000 teeth that hadrosaurs had in their jaws, which would have been extremely well-suited to grinding grass.

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horses nostrils blowing steam
Pavlina Trauskeova/Shutterstock

Physical changes…

…to the heads and bodies of these grass munchers would eventually have evolved. As BBC Future pointed out, “Horses and cows have flattened muzzles useful for cropping tough, low-lying vegetation.” Grass-eating, duck-billed dinosaurs might have developed squared-off snouts, and “sauropod necks might have shortened to aid grazing at their feet.” Learn the truth about these dinosaur “facts” scientists wish you’d stop believing.

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Cracked soil ground holes .

Dinos that burrow?

“It’s odd that dinosaurs didn’t really [burrow], as it’s a common way of life among lizards and snakes,” paleontologist Paul Barrett told BBC Future. “Given more time, some dinosaurs might have become subterranean specialists—the scaly or feathery equivalent of mammalian moles,” the article notes. Learn about some of the Earth’s tiniest creatures that play a huge role in the environment.

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Arctic Icebergs on Arctic Ocean in Greenland

Furry…but probably still not cuddly

Some dinosaurs before the asteroid hit were living up above the Arctic Circle, in conditions that were considerably warmer than what was to come with various ice ages over the millennia. Naish wonders if some of them would have developed “thick and elaborate pelts, covered in fuzz and feathers all the way down to the tips of their toes and tails.” A woolly T. rex? Now that’s the stuff of nightmares—and so is the fact that these 14 animals could go extinct in our lifetime.

Lela Nargi
Lela Nargi is a veteran journalist covering science, sustainability, climate, and agriculture for Readers Digest, Washington Post, Sierra, NPR, The Counter, JSTOR Daily, and many other outlets. She also writes about science for kids. You can follow her on Twitter @LelaNargi.