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What If the Asteroid Never Killed the Dinosaurs?

VO: Ashley Bowman WRITTEN BY: Sean Harris
Written by Sean Harris It's one of the most defining moments in the history of Planet Earth. Crashing into the Yucatán Peninsula, 66 million years ago, the asteroid that wiped out the dinosaurs caused unprecedented damage, destruction and devastation. But what if that massive rock had missed? Would dinosaurs still exist? would the rise of the mammals ever have happened? And would we be here today? Expect an alternate reality of prehistoric proportions, as we investigate how the world would be different.

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What If the Asteroid Never Killed the Dinosaurs?

There are surely few more momentous moments in the history of the Earth than when a 6.2 mile or 10-kilometre-wide asteroid struck our planet, around 66 million years ago. Hurtling into the Yucatán Peninsula of modern-day Mexico, the cataclysmic impact caused an explosion several billion times as powerful as the Hiroshima atomic bomb, to trigger megatsunamis, massive volcanic eruptions and worldwide wildfires. A thick blanket of ash, debris and soot suffocated all types of until-then liveable environments, blocking out the sun, sending everything into darkness and causing temperatures to rise and fall to unparalleled extremes. It was doomsday for the dinosaurs.

Having reigned on Earth for more than 180 million years, the dinosaurs were wiped out by one colossal chunk of space rock that just so happened to cross their planet’s path. But, while traditional theories often imply that the death and destruction were almost instantaneous, contemporary science has cast more than a few questions over exactly how, when and why the dinos died.

Some scientists suggest that dinosaurs were already in decline even before the asteroidal event. Their evolutionary heyday is usually considered as the late-Triassic Period, around 220 million years ago, when new species were appearing and evolving far quicker than others were dying out. However, around 120 million years later, so around 40 million years before the asteroid impact, dino-populations were falling fairly fast – particularly among the meat-eating theropods, including the Tyrannosaurs. The downturn wasn’t a blanket rule for all species, but the dinosaurs’ dwindling fortunes may have contributed to their eventual inability to survive their own apocalypse.

On the other side, some theories argue that the dinosaurs would’ve easily (and inevitably) regained their upward curve, had the asteroid never happened – or if it had hit the oceans rather than land. Sure, some species figures had been in decline, but the trend wasn’t entrenched, and extinction would’ve still seemed almost impossible. In fact, some scientists say that some species of dinosaur may still have walked the Earth between 30,000 and 300,000 years even after the asteroid hit. So, that fateful rock may not have been the absolute final straw, but it almost certainly marked the beginning of the end.

But, what if it never happened at all? What if the asteroid had just missed Earth, the ancient ecosystems had continued to flourish, and the dinosaurs had never even encountered instant atmospheric Armageddon – because it was never inflicted upon them? What might the world be like, now?

In the days, weeks and months after the asteroid, it was definitely ‘survival of the smallest’. The largest dinosaurs were worst affected, mostly because the disaster decimated the food chain, leaving the bigger beasts with nowhere near enough to eat. Edible creatures were understandably hard to come by, and plant stocks were severely depleted given the dramatic changes in temperature, weather and soil. All of this was essentially good news for us humans, because it meant that a very small number of early mammals (which were tiny, in comparison) could survive while their predators perished. Of course, in a world without the asteroid, this shift isn’t likely to have happened, so there’s no real reason to believe that the rise of the mammals would ever have occurred – so you and everyone else would never have existed.

The asteroid directly (or indirectly) killed off around three-quarters of the planet’s species at that time, and while there is evidence that some dino-breeds may have eventually disappeared through natural selection, it’s probable that the majority would have continued to develop. It’s true that many of today’s birds are actually distant descendants of various avian creatures from many millions of years ago, but the land-dwelling lizards were also far more intelligent and adaptable than modern stereotypes imply. And that’s partly because some of them were less lizard-like than we often imagine. There’s evidence that some dinosaurs were at least partly warm-blooded, so particular species could’ve easily applied themselves to any Ice Age thrown their way – and continued to thrive across all regions and environments on Earth.

Major fossil finds are typically uncovered in dry and dusty desert landscapes, but that’s mostly because these areas are where bones are best preserved and most easily accessible – and not because they’re the only locations where dinosaurs lived. A 2015 discovery of the Ugrunaaluk kuukpikensis in arctic Alaska has contributed to an ever-growing appreciation of just how far dinosaur populations had spread. So, had they not been halted by the asteroid, their all-conquering versatility would’ve likely increased. Today, the word ‘dinosaur’ has come to mean anything that’s clumsy or outdated, but that description was probably far from true for the seemingly unstoppable creatures themselves.

It’s almost impossible to guess how the dinosaurs would’ve evolved over the 66 million years since the Cretaceous Period was suddenly ended, but most theorists agree that there would’ve been significant changes. World famous forms such as the Tyrannosaurus Rex and Triceratops would no doubt have dramatically altered to suit their developing environments. For a measure of what can be achieved within the time frame, just consider the mammals’ progress from small, shrew-like lifeforms into today’s dominant and diverse creatures – the improvements are obviously vast. And, given that the dinosaurs seemed to deal solely in superlatives, the fastest, strongest, tallest and longest species are likely to have become even more incredible in size and shape.

The development of dinosaur intelligence would’ve been key, and has been subject for continuous speculation – with the Troodon usually taking centre stage. Troodon boasted a comparatively large brain for its relatively small size, and is thought to have been one of the smartest dinosaurs at the point of extinction. It walked on its hind legs and had large, forward-facing eyes, leading many to muse that the cleverest dinosaurs were headed for a more human-like body-shape.

The so-called ‘dinosauroid’ might’ve become fully bipedal while retaining scaly skin, sharper teeth and clearer vision – to look something like the stereotypical Area 51 alien. However, many palaeontologists argue that this vision is only the product of human arrogance, as there’s little reason to believe that future dinosaurs would’ve looked anything like us – barring an enormous evolutionary coincidence. The human design is good, but alternative options are endless, and our forms aren’t an undisputed end-goal for all living things.

That said, had the dinosaurs been allowed to evolve and improve for millions of years more, the emergence of mammals would’ve been increasingly difficult, if not impossible. Dinosaurs so conclusively dominated the food chain that even had their numbers fell, the opportunities for a species overhaul would’ve been basically non-existent. Dino intelligence may never have expanded into anything to match our own – crocodiles have been on Earth longer than us, and they’re not running for president yet – but that wouldn’t matter so long as they topped the natural order. And who or what was ever going to challenge them?

So, if the asteroid had never killed the dinosaurs, the chances are that untold future versions of the Velociraptor and co. (with or without human-standard brains) would still be roaming the wilds of Earth today – unless the planet presented an alternative means of extinction. Namely, global warming.

It may feel like a modern phenomenon, but global warming and climate change did (and hypothetically would have) caused major problems for the dinosaurs, too. The Mesozoic Era – formed of the Triassic, Jurassic and Cretaceous Periods – played host to large-scale changes on Earth, not least the break-up of Pangaea into separate land masses that eventually became the seven continents of today.

As a general rule, the planet was thriving until the asteroid hit, in some parts like a show garden in full bloom. Flowers were emerging and plants were diversifying. But atmospheric changes, including shifts in carbon dioxide and oxygen levels, were too much for some species. Coupled with widespread and unprecedented volcanic eruptions both before and after the asteroid impact, the world might’ve been well on its way to wiping out the dinosaurs, anyway. The space rock just cleared the slate quicker. In time, this might’ve set the scene for an alternative rise of the mammals, just at a later point in history. Or, it might’ve ushered in an altogether different dominant species.

Obviously, we’ll never know for sure. But we’re alive to even consider the possibilities (at this exact point in time) thanks in large part to that famously wayward, world-ruining rock. Twenty-first century dinosaurs never became a reality, but even if they had, then we more than likely wouldn’t be here to appreciate them. The day the asteroid hit was a death knell for the dinosaurs, but a new beginning for us, sparking 66 million years’ worth of awesome evolution, all so that you can watch this video today.

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