Getting Rid Of Teeth May Have Given Birds An Evolutionary Advantage Over Predators

A young wild owl reacts as it is measured, weighed and ringed in a zoo in Arnhem, Netherlands, on May 23, 2018. Beaks may allow for a shorter incubation and less time being vulnerable to predators. Piroschka van de Wouw/AFP/Getty Images

Birds don't have teeth, and believe it or not, we're still not entirely sure why. A new study, however, has an impressive theory on what happened to our winged friends, and suggests how going toothless gave them, and their dinosaur ancestors, an evolutionary edge.

The study, published online in Biology Letters Wednesday, suggested that birds lost their teeth so that incubating babies could hatch quicker. This challenges past theories that suggested birds lost their teeth to aid in their ability to fly or to improve their ability to eat. However, some flying dinosaurs did have teeth and some meat-eating dinosaurs also lost theirs. For this reason, faster incubation appears to be the most sensible answer.

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According to the research, developing teeth can take up 60 percent of egg incubation time, reported. The ability to hatch faster meant that birds would spend less time vulnerable to predators or natural disaster as eggs, and have a better chance of survival.

"We suggest that (evolutionary) selection for tooth loss (in birds) was a side effect of selection for fast embryo growth and thus shorter incubation," wrote researchers Tzu-Ruei Yang and Martin Sander from the University of Bonn in Germany, reported.

Modern birds descended from a group of dinosaurs called theropods. These two-legged dinosaurs included ferocious meat eaters, such as Tyrannosaurus and some velociraptors, Scientific American reported. In fact, certain features such as having feathers existed long before birds did. In order to understand why birds evolved beaks, the researchers looked at their prehistoric ancestors.

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Last year, a study concluded that eggs of non-flying dinosaurs took longer to incubate than scientists previously thought. Further examination concluded that this extended incubation time was dedicated to tooth formation. For example, the research revealed that the incubation period for dinosaurs with teeth is several months, while birds are only a few days to a few weeks.

While this theory seems to fit, it is not without holes. For example, turtles also have beaks instead of teeth, but have retained their long incubation period, the team noted. The researchers were not able to explain this anomaly, and perhaps the mystery of birds' beaks will forever remain just that.