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.
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