A team of researchers have reverted the beak structure of a chicken embryo back to its ancestral state—a time when dinosaurs roamed the land with snouts instead.
"The beak is a crucial part of the avian feeding apparatus, and is the component of the avian skeleton that has perhaps diversified most extensively and most radically—consider flamingos, parrots, hawks, pelicans, and hummingbirds, among others," Bhart-Anjan S. Bhullar, lead author of the study published in the journal Evolution, explained. "Yet little work has been done on what exactly a beak is, anatomically, and how it got that way either evolutionarily or developmentally."
There are two different genes that a developing embryo needs in order to construct a bird skull with a beak. The team decided to see what happened when they repressed those genes. To do this, they used small-molecule inhibitors to block the beak genes. The effects were shocking.
The beak structure of the chicken embryo returned to its ancestral anatomy, along with the palatine bone on the roof of the mouth. The skull of the chicken embryo developed a reptilian 'snout' instead of a beak. Two bones manifested themselves in this snout-like structure, which is reminiscent of the nose of a modern-day alligator. "This was unexpected and demonstrates the way in which a single, simple developmental mechanism can have wide-ranging and unexpected effects," Bhullar said.
The skull of a chicken embryo ready to hatch has a beak (left), but when certain proteins are blocked (middle), it develops a reptilian 'snout' from two bones, rather like a modern-day alligator (right) via Bhart-Anjan Bhullar
The chickens didn't actually develop snouts, per se, but changes to the actual embryo are noticeable: There is a little flap of skin covering the gene-altered chicken-embryos' would-be beaks.
It must be noted that the genetically altered embryos were never hatched. "Our goal here was to understand the molecular underpinnings of an important evolutionary transition, not to create a 'dino-chicken' simply for the sake of it," said Bhullar.
We are still far from identifying the genetic changes that are responsible for nature's first beaks, but identifying the genes involved is a great start. The team won't be building a zoo of little dino-chickens anytime soon. The purpose of this experiment was to examine the evolutionary pathways on a molecular level, not create a real-life Jurassic Park.