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Birds — like anteaters , baleen whales and turtle — do n’t have tooth . But this was n’t always the case . The rough-cut ascendant of all know raspberry rollick a solidifying of pearly-white whites 116 million years ago , a new study regain .
In the work , researcher look at the mutate clay of tooth genes in mod birds to figure out when hiss developed " edentulism " — an absence of teeth . Ancient bird have left only a fragmentedfossil record , but learn the genes of New birds can help elucidate how the bird lineage has changed over time .
An Archaeopteryx fossil discovered in Germany
" DNA from the crypt is a powerful tool for unlocking secrets of evolutionary history , " Mark Springer , a professor of biology at the University of California , Riverside and one of the study ’s lead researchers , said in a command .
Modern birds have curve beak and a hearty digestive tract that help oneself them cranch and process intellectual nourishment . But the 1861 finding of thefossil birdArchaeopteryxin Germany suggested that birds descended from jagged reptilian ancestors , Springer order . And scientists now know that birdsevolved from theropod dinosaur , carnivorous beast such asTyrannosaurus king , which had a lip full of sharp tooth .
But no one knew exactly what go on to the tooth in the evolution of these brute from then until now . " The history of tooth loss in the derivation of modern birds has remained problematical for more than 150 years , " Springer said . [ 8 Foods for Healthy Teeth ]
An Archaeopteryx fossil discovered in Germany
In the new study , the researcher marvel whether the bird lineage lost its teeth in a single event , meaning the common ascendant of all hiss did not have teeth , or whether edentulism happen independently , in dissimilar blood of fowl throughout history , the researchers said .
To come up out , they investigated the factor that regularize tooth production . In vertebrates , tooth formation imply six genes that are crucial for the formation of enamel ( the backbreaking tissue that coats teeth ) and dentin ( the calcified stuff underneath it ) .
The research worker looked for mutations that might deactivate these six genes in the genome of 48 razzing metal money , which comprise almost every order of survive birds . A mutant in dentin- and enamel - tie in genes that was shared among bird species would indicate that their vulgar ancestor had lost the ability to form teeth , the researchers said .
They found that all of the bird coinage had the same mutations in dentin- and tooth enamel - related gene .
" The front of several inactivating mutations that are partake by all 48 birdie specie suggests that the outer enamel get over of tooth was lost around 116 million years ago , " Springer tell .
The researchers also found mutations in the in the enamel and dentin genes of other vertebrates that do n’t have teeth or enamel , include turtles , armadillos , sloths , aardvarksandpangolins , which wait like scaly anteaters .
The closest living modern reptile relation of birds is thealligator , Springer said . " All six factor are functional in the American alligator , " Springer said .
This tooth finding is one of many that came out of a large - scale leaf scientific effort to study theevolution of bird . The findings of that effort were published today ( Dec. 12 ) in the journal Science , and in several other journals .
