Artist’s impression of how dinosaurs could have looked, if they had survived © James Gilleard
Around 66 million years ago, a 14km-wide asteroid smashed into our planet. An estimated 15 billion tonnes of soot spread through the atmosphere, creating one long night that lasted several years and made photosynthesis all but impossible. It heralded an endless winter that saw average temperatures fall by as much as 28C. These are the conditions that the few wretched creatures that survived the initial impact had to endure – not to mention the earthquakes, tsunamis, wildfires and volcanic eruptions that swiftly followed in its wake.
Around three-quarters of all species went extinct and no animal bigger than a Labrador dog survived. But according to researchers at the University of Texas, things could have been very different. They reported findings that had the asteroid struck Earth just a few minutes earlier, it would have hit the deep ocean rather than the shallow sea of the Yucatan Peninsula in present-day Mexico.
Had that been the case, then the damage would have been more localised. Some of the dinosaurs far from the impact site might have survived, and the world would be a different place today. In our own history, only the feathered theropod dinosaurs (a group of bipedal dinosaurs) we know as birds made it through the calamity, but how would things have turned out if their larger relatives had joined them? Would dinosaurs still be alive today and could mammals such as humans have evolved? What would our world look like if we shared it with the descendants of animals like T. rex and Triceratops?
“I’m sure a fairly nice diversity of non-avian dinosaurs would still be here,” says Dr Stephen Brusatte, a palaeontologist at the University of Edinburgh. “If there was no sudden, catastrophic shock of the asteroid, I really don’t see anything that’s happened since – whether it was the spread of grasslands; changing ocean currents; the separation of Antarctica from South America, which caused a cold snap; or the more recent Ice Ages – that would have knocked off the dinosaurs.”
Over the years many have tried to imagine what kind of creatures dinosaurs might have evolved into had they survived. The most famous attempt is a 1988 book called The New Dinosaurs: An Alternative Evolution, by Scottish geologist and author Dougal Dixon. For this magnificent work of speculative zoology, Dixon conjured up creatures such as the ‘cutlasstooth’ – a pack-hunting, sabre-toothed predator from South America; the ‘cribrum’ – a flamingo-like, filter-feeding theropod from Australia; and the ‘gourmand’ – a relative of T. rex that lost its front limbs entirely and developed a distensible jaw to allow it to rapidly swallow prey whole, much like a snake.
Perhaps this last idea isn’t entirely wide of the mark. Dr Tom Holtz, an expert on theropod dinosaurs at the University of Maryland in the US, says that both tyrannosaurs and abelisaurs, the two types of big meat-eater present in the Late Cretaceous, are notable for their tiny forelimbs. “Given that arms were non-critical for hunting, it’s possible that a Cenozoic [current geological era] tyrannosaur could…
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