New research has provided the evolutionary answers to why the beak replaced teeth. Source: News Corp Australia

Ever since a fossil of the ancient bird Archaeopteryx was discovered in 1861, scientists have known that avian ancestors once had teeth while birds today lack those pearly whites. But when birds “lost their teeth” has remained a mystery — until now.

A new study suggests that the common ancestor of all living birds lost the ability to produce teeth, and the answer to exactly how this happened can be found in modern-day birds’ genes.

For the study, the researchers examined the genomes of 48 living bird species, taking a close look at six genes associated with tooth formation.

What did they find? It turns out that all of the bird species share genetic mutations that inactivate genes involved in the formation of both tooth enamel and the portion of the tooth called dentine.

Birds went from teeth the beak. Source: News Corp Australia

Based on the mutations, the researchers think that a common ancestor of the birds lost the enamel caps on its teeth around 116 million years ago. And around that same time, birds’ beaks came into play.

“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,” study co-author Dr. Mark Springer, a biology professor at the University of California, Riverside, said in a written statement.

Birds aren’t the only “edentulous” (or toothless) modern-day vertebrates. Since turtles and pangolins are also missing teeth, the researchers examined their genomes and found similar results.

“All edentulous vertebrate genomes that we examined are characterised by inactivating mutations,” Springer said in the statement. “The dentine-related gene DSPP is functional in vertebrates with enamellers teeth — sloth, aardvark, armadillo. All six genes are functional in the American alligator, a representative of Crocodylia, the closest living relatives of birds.”

With no tooth aches, no wonder everything is such a laugh. Source: News Corp Australia

The study was published in the journal Science.

This article originally appeared in The Huffington Post and was published with permission.