Using fossils and a large comparative analysis of modern animals, Dr. Balanoff and a team of evolutionary biologists, led by Shuo Wang from the Capital Normal University in Beijing, found that the loss of teeth and the emergence of beaks are connected processes in theropods. As the beak grew across the dinosaur’s face, it also inhibited the growth of teeth, the team suggested. On an evolutionary scale this transition happened until theropods developed mouths that resembled the bird beaks seen today.
In earlier research, Dr. Wang’s team discovered an emu-like theropod called Limusaurus that began life as a baby with teeth, but lost them as it grew older and morphed into an adult with a beak. [above]
For their most recent paper, he and his colleagues examined more dinosaur jaw fossils and found two other theropods that underwent transitions similar to Limusaurus: an early Cretaceous bird called Sapeornis, which resembled modern birds, and a small caenagnathid oviraptorosaur, which resembled a velociraptor but with a beak.
“This demonstrates an evolutionary process of the beak for the first time,” said Dr. Wang.
Saturday, September 30, 2017
How Dinosaurs Lost their Teeth
good new science about how the transition took place: