When an asteroid the size of Mount Everest collided with our planet about 66 million years ago, dinosaurs that were slowly diminishing by numbers had gone extinct.

But not all of them. Scientists say that a class of theropod dinosaurs with feathers - the ancestors of birds - managed to live on. How did this happen? It's all thanks to seeds.

The Role Of Seeds In Survival

Most of the bird-like dinosaur species died off during the massive extinction event millions of years ago, but several survived. New research suggests that munching on seeds would have kept the bird-like dinosaurs alive throughout the widespread destruction of the time.

Seeds would have been the most abundant resource for food. Although plants would have found it difficult to grow with the sudden climate change as well as other effects of the asteroid impact, seeds were more resilient.

Researchers led by Derek Larson said the seeds were tucked in the soil, making them viable for as long as 50 years.

How Bird Ancestors Survived

Modern birds are believed to have come from the lineage of maniraptoran dinosaurs, small carnivorous theropod dinosaurs whose diet were supported by a mouth full of teeth.

Those same teeth would have made it harder for bird-like dinosaurs to munch on seeds after the asteroid event, so instead, the toothless and beaked members of this species would eat their way to survival.

But filling an evolutionary gap was not easy. Thomas Williamson, not a member of the research team, said there little is known about tiny theropods during the late Cretaceous period.

So, to find an answer to this mystery, Larson and his team looked into the state of maniraptoran dinosaurs during the end of the Cretaceous period, working backwards in the timeline.

They examined more than 3,000 fossilized teeth - all of which comprised a time span of about 18 million years - from four different families of maniraptoran dinosaurs.

Tracing modern bird diets, the team concluded that the last common ancestor between bird-like dinosaurs and modern birds would have been toothless, beaked seed eaters.

Larson said maniraptoran dinosaurs with teeth existed up until late Cretaceous, but they went extinct. He said groups of beaked birds may have survived the mass extinction because they could eat seeds.

"I hope in the future that we find a fossil animal that helps corroborate our arguments," added Larson.

In the meantime, the findings of the study are featured in the journal Current Biology.