One fateful day 66 million years ago, the dinosaurs — which had inhabited Earth for about 165 million years — got a nasty surprise: A roughly 9-mile-wide (15 kilometers) asteroid crashed into what is now Mexico, triggering tsunamis, wildfires and acid rain and causing vast amounts of debris to block out the sun. As a result, 75% of species on Earth, including the nonavian dinosaurs, died off within months of the impact.
But what if the asteroid had never struck Earth? Would the dinosaurs have continued their reign over the planet? Could they have survived ice ages and evolved to become more intelligent?
According to paleontologists, it's possible that dinosaurs would have continued to evolve and rule Earth. After all, they'd already survived and adapted for 165 million years, which included surviving rising and falling seas, temperature spikes and volcanic eruptions, according to Steve Brusatte, a professor of paleontology at the University of Edinburgh. But this would have made it impossible for our mammal ancestors to evolve the way they did.
Some scientists think dinosaurs would have met their doom anyway because extinctions appear to have outpaced the emergence of new dinosaur species. But Brusatte isn't convinced.
"For those of us who collect fossils of the last dinosaurs, we can see quite clearly that everywhere in the world … there [was] a great diversity and abundance of dinosaurs," Brusatte told Live Science in an email. "It seems remarkably clear to me that dinosaurs were strong, successful, still diverse, [and] still at the top of their game when the asteroid hit."
Related: What happened when the dinosaur-killing asteroid slammed into Earth?
Dinosaurs in an ice age?
But could dinosaurs have lived in frigid conditions, such as ice ages? With the exception of some dinosaurs that lived in snowy climates, the majority didn't. According to Brusatte, some dinosaurs may have fared well under new extreme conditions.
"Many of them had feathers, [so] they could insulate themselves just like mammals can," Brusatte said. In addition, some dinosaurs, such as Tyrannosaurus rex, were likely warm blooded, research finds, meaning they weren't completely at the mercy of a changing climate.
It's also possible that dinosaurs would have evolved new defenses against the cold during extreme weather. Take mammoths, for example, which evolved around 5 million years ago in South Africa. About 800,000 years ago, during the last ice age, some mammoths grew woolly coats as they expanded to the much colder region of Eurasia.
Would dinosaurs have evolved to be more intelligent?
Given enough time, could dinosaurs have evolved into more intelligent creatures? In a 1982 thought experiment, American-Canadian paleontologist Dale Russell wondered whether troodontid dinosaurs could have evolved sentience had they not died in the end-Cretaceous mass extinction. He dubbed them humanoid dinosaurs, or dinosauroids. He based this idea on the fact that one species of troodontid already had a "large brain, stereoscopic vision, opposable fingers and bipedal stature," and might have evolved to have an "encephalization quotient similar to that of Homo sapiens" if it had survived. His collaborator Ron SĂ©guin, an artist and model maker, made a reconstruction, showing a green-skinned creature.
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Source: LiveScience
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