Friday was a big day for bird lovers: Twenty-three new papers revealed all kinds of scientific information about the animals, ranging from how they learn to sing to how they got their feathers, Australia's ABC reports. Among the reports was one looking into how the creatures lost their teeth. Experts know from the bird ancestor Archaeopteryx that the animals once had teeth. But it's been a longstanding scientific mystery whether several different ancestors of today's birds separately stopped growing teeth—or whether a single ancestor common to all birds was behind the dental disappearance.
Turns out that the latter theory was correct, the study says: Some 116 million years ago, a common ancestor to today's birds lost its teeth, ABC notes. Researchers reached their conclusions by investigating 48 different bird species, representing nearly all orders of today's bird family tree, LiveScience reports. All these species had the same mutations in six genes related to tooth development, pointing to the common-ancestor theory. Those "inactivating mutations" suggest "that the outer enamel covering of teeth was lost around 116 million years ago," a researcher says. (A mere 90 million years ago, toothless "dragons" soared through the air.)