Scientists still don't totally agree on what happened to the planet 66 million years ago — an asteroid impact? a volcanic eruption? both at the same time? — but they know it wasn't good.

In a mere blip of geological time, 70 percent of all species were obliterated from Earth. Those that survived did so mostly by keeping their heads down: hiding underground, diversifying their eating habits and generally making the best of less-than-ideal circumstances.

This was probably the secret to the success of feathered theropods — better known as the ancestors of today's birds — the only dinosaurs to pull through the mass extinction. According to a study published Thursday in the journal Current Biology, one small secret may have saved these ancient creatures: seeds.

"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," lead researcher Derek Larson, a paleontologist at the University of Toronto, told the BBC.

Bird-like dinosaurs with beaks, rather than toothy jaws meant for chowing down on plants and animals, would have been able to snap up the seeds that persisted on the devastated landscape while other food sources withered.

"We think that the survival of birds had something to do with the presence of their beak," Larson added.

The theory comes from an analysis of thousands of fossilized teeth from maniraptoran dinosaurs, a clade of small creatures thought to be the precursors of today's birds. Most of them were carnivorous and had blade-like or jagged-edged teeth —  those species swiftly disappeared during the mass extinction event, suggesting that something they had in common doomed them all.

Paleontologists haven't yet found a fossil of a beaked survivor (maniraptor bones are delicate, according to the Toronto Star, so the more durable teeth are often the only fossils available), but Larson's research indicates that there was one. By analyzing the diets of modern birds, he reconstructed a hypothetical ancestor and came to the conclusion that it probably had a short, robust beak for eating seeds.

"I think that's brilliant," David Fastovsky, a paleontologist at the University of Rhode Island who was not part of this study, told the Christian Science Monitor. "I don't know why we didn't think of it."

Larson said he still hopes to find a fossil to confirm his theory. But in the meantime, modern ecological disasters may help support his findings.

David Evans, curator of vertebrate paleontology at the Royal Ontario Museum and another of the paper’s authors, told the Toronto Star that seed-eating vertebrates like beak-y birds are often the first creatures to return to a forest after a devastating fire.

"This makes sense, because a forest fire will burn all the foliage and decimate the animal population, but seeds are in their protective shell," he said. "They survive these major disruptions, and they can survive for decades.”

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