Biologists have created chicken embryos with dinosaur-like faces by successfully replicating the molecular process that made dinosaur snouts evolve into bird beaks.
A team of researchers, led by paleontologist Bhart-Anjan Bhullar of Yale University, and Harvard University evolutionary biologist Arhat Abzhanov, used the fossil record to reverse the features of a bird's skull for the first time.
Chicken embryos were transformed into specimens with a snout and palate similar in appearance to that of small dinosaur ancestors, such as the Velociraptor, in order to determine how snouts might have changed into beaks 150 million years ago.
However, the research, published in journal Evolution, isn't an attempt to engineer "dino-chickens" or resurrect dinosaurs in an echo of Jurassic Park. "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.
The study casts new light on the far-from-smooth evolution of dinosaurs into modern-day avians. Initially, the first birds were indistinguishable from their carnivorous Jurassic ancestors. But as birds evolved, the premaxilla -- the twin bones forming a reptilian snout -- grew longer and fused into a beak. "Yet little work has been done on what exactly a beak is, anatomically, and how it got that way either evolutionarily or developmentally," Bhullar explained.
Bhullar and Abzhanov analysed the embryonic development of chicken and emu beaks, alongside the snouts of lizards, alligators and turtles, and concluded that reptile and dinosaur snouts developed in a similar way. It seems it was bird evolution that altered the development of the snout.
By using small-molecule inhibitors to block the proteins FGF and Wnt -- known to be crucial in the development of birds' faces, and distinct from reptile embryos -- the scientists successfully induced the ancestral molecular anatomy. The results were surprising: not only did the structure of the beak revert, but the palatine bone on the roof of the mouth went back to its ancestral state too. Bhullar commented: "This was unexpected and demonstrates the way in which a single, simple developmental mechanism can have wide-ranging and unexpected effects."
The researchers, who travelled from alligator nests in southern Louisiana to a Massachusetts emu farm as part of the study, never actually hatched the dino-chicks, but rather studied the subtle differences between the altered and non-altered chicks. Noting that the dino-chicks still had a flap of skin covering their fledgling beaks, Bhullar said: "Looking at these animals externally, you would still think it's a beak. But if you saw the skeleton, you'd just be very confused."
After creating digital models of the embryos' skulls, the scientists discovered that some more closely resembled early birds such as Archaeopteryx and dinosaurs such as Velociraptors, rather than modern-day chickens.
Bhullar's team now plans to study the expansion of mammals' skulls and the unusual lower limbs of crocodiles by using similar techniques to bring ancient anatomy "back to life". Bhullar said: "I think it will open as big a window as you could possibly get into the deep past without having a time machine."
This article was originally published by WIRED UK
