By Helen BriggsBBC News
22 April 2016
Modern birds owe their survival to ancestors who were able to peck on seeds after the meteor that wiped out most dinosaurs, say scientists.
Bird-like dinosaurs with toothless beaks survived the "nuclear winter" that followed the meteor strike, because of their diet, a study says.
The impact altered the climate of the Earth and blotted out sunlight.
The loss of vegetation would have deprived plant-eating dinosaurs of food. In turn, meat-eaters suffered.
But seeds still in the ground may have sustained small toothless bird ancestors until the planet began to recover.
The theory, outlined in the journal Current Biology, could explain why no modern bird has a beak lined with teeth.
"After this meteor, you're left with essentially a nuclear winter where really not much is growing, the plants aren't able to grow to provide nourishment for plant-eaters and then meat-eaters aren't able to access plant-eaters if they've all perished," said lead researcher Derek Larson, from the University of Toronto.
"We think that the survival of birds had something to do with the presence of their beak."