New Theory: Seed Diet Helped Birds Survive Mass Extinction

Modern birds should be thankful for the food habits of their ancestors. According to a new theory, scientists have suggested that birds survived the mass extinction caused by an asteroid collision 66 million years ago that wiped out a majority of life on earth due to their seed diet.

The asteroid strike caused a nuclear winter in its wake, an impact that blotted out sunlight and drastically changed the climate of the earth. Consequently, the unfriendly conditions on the planet led to a loss of vegetation which in turn brought about the scarcity of food for herbivorous dinosaurs. The phenomenon triggered a chain reaction which also affected the carnivores.

However, small toothless ancestors of birds continued to survive, all because of their diet. The dietary intake of prehistoric birds comprised of seeds that were still found on the ground, which could be easily picked up owing to their beak formation. The food was enough to sustain their survival until the planet began to recover.

According to the theory, which is outlined in the Current Biology journal, this is the reason why modern day birds don't have teeth lining their beak. "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 Derek Larson, lead researcher from the University of Toronto. "We think that the survival of birds had something to do with the presence of their beak."

The researchers analyzed more than 3000 fossilized teeth of maniraptorans, which were basically bird-like dinosaurs and also believed to be the closest relatives of modern birds, to develop their theory. The experts reconstructed a hypothetical bird and its likely diet by observing the food pattern of modern birds.

On the basis of their study, the researchers suggested that the ancestor of modern day birds was a seed eating bird with a strong, robust and short beak which could crush the seeds built in the ground, and make it their food source. Larson feels that most of the birds we see today would not have existed had it not been their seed diet, though a few insect-eating types might still have survived.