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Why birds don’t have teeth: asteroid strike left seed-eating dinosaurs at top of pecking order
If you have ever wondered why birds do not have teeth, science may finally have provided an answer.
A new hypothesis suggests that the ancestors of modern birds managed to survive the asteroid impact which finally wiped out the dinosaurs because they had beaks, and so could eat seed.
While meat-eating flying reptiles, like pterodactyls, struggled to find food following the catastrophic strike at the end of the Cretaceous Period, small bird-like dinosaurs rose to the top of the pecking order with their shell-cracking abilities.
Lead researcher Derek Larson, from the University of Toronto in Canada, said: "The small bird-like dinosaurs in the Cretaceous, the maniraptoran dinosaurs, are not a well-understood group.
"They're some of the closest relatives to modern birds, and at the end of the Cretaceous, many went extinct, including the toothed birds - but modern crown-group birds managed to survive the extinction.
"The question is, why did that difference occur when these groups were so similar?"
The scientists began by analysing collected data on more than 3,000 fossilised teeth from four different maniraptoran families.
They found that maniraptoran diversity continued right up to the end of the Cretaceous, 66 million years ago, suggesting a sudden extinction due to a catastrophic event.
The team suspected that diet might have played a part in the survival of lineages that produced today's birds.
Using published research about modern birds, including dietary information and inter-species relationships, the scientists inferred what their Cretaceous cousins might have eaten.
They hypothesised that the last common ancestor of today's birds was a toothless seed-eater with a beak.
The research, published in the journal Current Biology, suggests that some birds were able to survive the aftermath of the meteor impact by eating seeds.
The massive asteroid or comet strike would have temporarily altered the Earth's climate and blotted out the sun with dust.
Widespread vegetation loss would have robbed many plant-eating animals of their food source, and in turn large predators would have gone hungry.
But hardy seeds may have sustained the small toothless birds until the world began to recover.
"There were bird-like dinosaurs with teeth up until the end of the Cretaceous, where they all died off very abruptly," Mr Larson said.
"Some groups of beaked birds may have been able to survive the extinction event because they were able to eat seeds."