Birds lost their teeth some 116 million years ago

RIVERSIDE, Calif., Dec. 15 (UPI) -- Evolutionary biologists want all the details, all the answers. Answers to questions like: when did birds lose their teeth? Did a common ancestors go toothless, or did separate bird lineages ditch the pearly whites at a later date?

By examining the fossil record and analyzing the degraded tooth genes in bird DNA, a team of biologists at the University of California, Riverside and Montclair State University were able to confirm that one of birds' common ancestors made the switch more than 100 million years ago.

"One of the larger lessons of our finding is that 'dead genes,' like the remnants of dead organisms that are preserved in the fossil record, have a story to tell," Mark Springer, a professor of biology at UC Riverside and one of the study's lead authors, said in a press release.

Birds aren't alone in choosing to forego teeth. Turtles have also opted for the beak, and several groups of mammals have developed alternative oral feeding tools -- including anteaters, baleen whales and pangolins. Each of these animals, Springer says, has a common ancestor with teeth. In the case of birds, it's theropod dinosaurs.

But at some point -- between the theropods and the first species of birds -- the birds avian ancestors began swapping out teeth for a beak. After analyzing the decaying nature of six genes linked with the formation of teeth, scientists suggest the transformation was solidified by 116 million years ago.

"We propose that this progression ultimately resulted in a complete horny beak that effectively replaced the teeth and may have contributed to the diversification of living birds," Springer said.

The study was published Monday in the journal Science.