Like turtles, baleen whales and anteaters, birds don't have teeth. A new study claims that wasn't always the case however.

The discovery was part of a large-scale scientific effort on the study of the evolution of birds.  The findings claim birds were known to have teeth approximately 116 million years ago. The study included researchers analyzing modern birds and mutated remains of their tooth genes so that they could understand why the absence of teeth was developed in these birds.

One of the lead authors of the study, Mark Springer of the UC-Riverside, said that one of the more important findings of the study is that dead genes, like the remains of dead organisms that have preserved in the fossil record.

Springer said that the absence of teeth and the presence of a beak are trademark characteristics of the modern birds. He added that the source of origin of enamel-less and toothless vertebrates was their common ancestors which had enamel-capped teeth, according to the study.

Modern birds use a beak instead of teeth and a part of their digestive track. The formation of teeth in vertebrates is a difficult process involving a number of different genes, the scientists said, according to

Of those genes, six were highly important and played a big role in the creation of enamel and dentin. Scientists determined that 48 species of birds share mutations in enamel-related genes and dentin-related genes. This means the genetic system needed for the formation of teeth was lost in the ancestor common to modern birds.

"The presence of several inactivating mutations that are shared by all 48 bird species suggests that the outer enamel covering of teeth was lost around - 116 million years ago," said Springer.

The findings were published Dec. 12 in the journal Science, and in several other journals. 

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