The extinction of the dinosaurs was caused by a wave of "colossal bad luck", new research suggests.
If the asteroid strike had hit a few million years earlier when food chains were stronger and range of species bigger, dinosaurs would have stood a greater chance of survival, paleontologists led by the University of Edinburgh found.
However a combination of factors - including increased volcanic activity, changing sea levels and varying temperatures meant the strike occurred "at the worst possible time".
"The dinosaurs were victims of colossal bad luck," Dr Steve Brusatte, of the University of Edinburgh's School of GeoSciences, said.
"Not only did a giant asteroid strike, but it happened at the worst possible time, when their ecosystems were vulnerable."