From the time of the discovery of the Archaeopteryx fossil in 1861, it has been obvious that modern birds come from toothed ancestors.
A recent study claims that teeth loss in birds occurred 116 million years ago. The study was published in the Science journal by biologists at the UC Riverside and Montclair State University in New Jersey.
The scientists utilized the remains of tooth genes in birds to figure out when the birds lost their teeth. The study discovered that edentulism or absence of teeth used to occur in the common ancestor of all birds. The study is incomplete regarding cases of early 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, much like the remains of dead organisms, that have preserved in the fossil record also have a story to tell. The absence of teeth and the presence of a beak are trademark characteristics of the modern birds, said Springer.
He also added that the source of origin of enamel-less and toothless vertebrates was their common ancestors which had enamel-capped teeth. In the case of birds, that ancestor is the theropod dinosaur. In order of processing and grinding food, modern birds use a beak instead of teeth and a part of their digestive tract. The formation of teeth in vertebrates is a complex process involving numerous genes, said the scientists.
Out of those genes, six of them were highly important and played a great role in the creation of enamel and dentin. The scientists analyzed those six genes in 48 bird species genomes, which stand for almost all currently living birds. They found that 48 species of birds share mutations in both enamel-related genes and dentin-related ones.
This suggests that the genetic system needed for the formation of teeth was lost in the ancestor common to all 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.”