Dinosaurs were wiped off the face of the Earth by a sudden drop in temperature – not by a comet striking the planet, boffins claimed.
Scientists studying fossils in Norway have discovered the world’s seas plummeted 9C from 13C to just 4C around 137 million years ago.
They believe this was caused by a sudden change in the Atlantic Gulf Stream – a phenomenon many experts fear is about to happen again.
The temperature drop during the Cretaceous period would almost certainly have wiped out an ”abundance” of the world’s dinosaurs.
Researchers behind the ground-breaking study claim this would have been the first major step dinosaurs took on their eventual road to extinction.
Some experts believe the creatures were wiped out by one cataclysmic event 65 million years ago – such as a meteor hitting the planet.
But the new research suggests they were wiped out by a series of environmental changes – starting with a drop in sea temperatures.
The study was conducted by a team of scientists, led by Dr Gregory Price of Plymouth University, who examined fossils and minerals from Arctic Svalbard in Norway.
He found the drop in temperatures was so severe that numerous species of dinosaur previously living in warm, shallow seas, land and swamps would have died out.
Dr Price said the team’s research showed the drop in temperature happened when the Earth was in a ”greenhouse” climate – similar to now.
He said: ”The drop in temperatures may well have been caused by a change in ocean circulation, much like what is being predicted for the Gulf Stream.
”In the Cretaceous period, the Atlantic was much narrower but it would have featured a similar, northerly-flowing current.
”If it had stopped working it could have resulted in the melting of the ice caps, causing a sudden drop in temperatures.
”We believe dinosaurs were most likely to be cold-blooded creatures and would have needed the warmth to keep them alive. If they were unable to migrate south they could have been wiped out.
”Climate change is now very much on the agenda in trying to determine how the dinosaurs became extinct.
”We now believe that they died out gradually and it is very possible that this could have been caused by a series of climatic changes.”
The drop in temperature is thought to have occurred because high levels of CO2 were in the atmosphere which caused global temperatures to rise and polar ice to melt – a phenomenon currently predicted for Earth.
It is the equivalent of the predicted shut-down of the Gulf Stream ‘conveyor belt’ – which scientists have warned could take Europe into another ice age.
Dr Price has been visiting the Svalbard since 2005, collecting fossils and samples in an area famed for a number of palaeontological discoveries, including giant marine reptiles such as pliosaurs and icthyosaurs.
He added: ”The flourishing of the dinosaurs and a range of other data indicates that the Cretaceous period was considerably warmer and boasted a high degree of CO2 in the atmosphere.
”But over a period of a few hundred or a few thousand years, ocean temperatures fell from an average of 13 degrees centigrade to between eight and four degrees.”
