The dinosaurs would have survived the asteroid that smashed into Earth and wiped them all out had it not been for the rather poor – from their point of view – timing with which it arrived.
The demise of these scaly – or indeed, even feathery – overlords may not have happened if the space rock hit a few million years later or earlier, boffins have suggested.
Academics at the University of Edinburgh have analysed fossil records and used new analytical tools to examine the condition of Planet Earth back in the dying days of the reptile rulers' reign.
They claimed that the 10km-wide Goldilocks asteroid hit Mexico at exactly the right time 66 million years ago, when Earth was experiencing a period of intense volcanic activity, shifting sea levels and fluctuating temperatures.
This combination of threats was enough to destroy the dinos' food chain by wiping out plant-eating species which served as meals to nastier, carnivorous beasts like the Tyrannosaurus Rex.
When it hit, the asteroid would have caused all manner of apocalyptic events such as "tsunamis, earthquakes, wildfires, sudden temperature swings and other environmental changes", say the boffins. The food chain would have been pulled apart bit by bit, with the dinosaurs wiped out "once species after another".
The Edinburgh boffins claimed that if the dino-busting death rock had hit a few million years earlier or later, the dino kings might have survived. That might sound like a long time, but it's barely a few minutes in evolutionary terms.
In the period before the strike, dinosaurs were more diverse and the food chains were more robust, the researchers found, whereas if they had survived for a few million years more, more species would have evolved, perhaps making them more resilient to the conditions after the impact.
Dr Steve Brusatte of the University of Edinburgh's School of GeoSciences said: "The dinosaurs were victims of colossal bad luck. Not only did a giant asteroid strike, but it happened at the worst possible time, when their ecosystems were vulnerable. Our new findings help clarify one of the enduring mysteries of science."
The boffins' claims were made after an international team of palaeontologists led by the University of Edinburgh studied an updated catalogue of dinosaur fossils, most of which were gathered in North America. These were then used to create a picture of how dinosaurs changed in the years leading up to their demise.
Dr Richard Butler, of the School of Geography, Earth and Environmental Sciences at the University of Birmingham, said: "There has long been intense scientific debate about the cause of the dinosaur extinction. Although our research suggests that dinosaur communities were particularly vulnerable at the time the asteroid hit, there is nothing to suggest that dinosaurs were doomed to extinction. Without that asteroid, the dinosaurs would probably still be here, and we very probably would not."
A study summing up the research has been published in Biological Reviews. ®