Dinosaurs could be roaming the Earth today instead of humans if they had not fallen victim to “colossal bad luck”, according to new research led by Scottish scientists.
An international team of palaeontologists used the latest fossil records and analytical methods to reconstruct events leading to the demise of the prehistoric creatures around 66 million years ago.
Their research revealed the planet was experiencing major environmental upheaval during the few million years before a 10km-wide asteroid struck in what is now Mexico. This included extensive volcanic activity, fluctuating sea levels and dramatic temperature swings.
At this time, the dinosaurs’ food chain was weakened by a lack of diversity among the large plant-eaters on which carnivores preyed, which is thought to have been caused by changes in the climate and environment.
This created conditions that left dinosaurs ill-equipped to survive the aftermath of the enormous asteroid strike.
The impact, which left a 150km-wide crater in the Yucatan peninsula, would have caused tsunamis, earthquakes, wildfires, see-sawing temperatures and other environmental changes.
The resulting collapse in food chains would have caused the dinosaur kingdom to be wiped out, one species after another.
The only animals to survive were those that could fly, and these evolved to become the birds of today.
The researchers suggest dinosaurs would likely have survived the catastrophe if the asteroid had hit earth a few million years earlier, when the range of species was more diverse and food chains more robust, or later, when new species had evolved.
“The dinosaurs were victims of colossal bad luck,” said geoscientist Dr Steve Brusatte, of the University of Edinburgh, a lead researcher on the study.
“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.”
Co-researcher Dr Richard Butler, of the University of Birmingham’s school of geography, earth and environmental sciences, 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.”
The palaeontologists studied an updated catalogue of dinosaur fossils, mostly unearthed in North America, to create a picture of how dinosaurs changed over the few million years before the asteroid hit.
They hope that studies in Spain and China will widen the understanding of events.
Dinosaurs were a diverse group of animals that first appeared during the Triassic period, 230 million years ago. They were the dominant terrestrial vertebrates for 135 million years, from the beginning of the Jurassic period, about 200 million years ago, until the end of the Cretaceous period.
Fossil records indicate birds evolved from theropod dinosaurs during the Jurassic age and so are considered a subgroup of dinosaurs by many experts.
The study, supported by the European Commission and the US National Science Foundation, was led by the Universities of Edinburgh and Birmingham, in collaboration with the University of Oxford, Imperial College London, Baylor University and University College London.