The fate of the dinosaurs may have been sealed half a billion years before life even appeared, by two geological time bombs that still exist near our planet’s core. A controversial new hypothesis links massive eruptions of lava that coincided with many of the Earth’s largest extinctions to two unusually hot sections of mantle 2,800 kilometres beneath the Earth’s crust. These sections formed just after the Earth itself, 4.5 billion years ago. If the hypothesis is correct, they have periodically burst through the planet’s crust, creating enormous oceans of lava which poisoned the atmosphere and wiped out entire branches of the tree of life. Debates still rage over what caused different mass extinctions, including the one that wiped out the dinosaurs. An asteroid that smashed into the Earth 65 million years ago is no doubt partially to blame for the demise of the dinosaurs. But, a less-known school of thought has it that this and other extinctions occurred when cracks in the crust let huge amounts of lava pour out from the centre of the Earth. Each event flooded at least 100,000 square kilometres, leaving behind distinct geological regions known as large igneous provinces (LIPs), such as India’s Deccan traps, which were formed during the time when the dinosaurs became extinct.