How Bird Beaks Evolved from Dinosaur Snouts

Where did the bird's beak come from? In order to answer that question, you need to take a look back at dinosaurs--and that's exactly what a team of scientists did. Using the fossil record as a guide, researchers have conducted the first successful reversion of a bird's skull features.

"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 Bhart-Anjan S. Bhullar, one of the researchers, in a news release. "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. Yet little work has been done on what exactly a beak is, anatomically, and how it got that way either evolutionarily or developmentally."

In this latest study, the researchers conducted a quantitative analysis of the anatomy of related fossils and extant animals to figure out how the transition occurred. Then, they searched for possible shifts in gene expression that would cause the transition. More specifically, they looked at gene expression in the embryos of emus, alligators, lizards and turtles.

So what did they find? It turns out both major living lineages of birds differ from the major lineages of non-bird reptiles, such as crocodiles, turtles and lizards, and from mammals. The birds have a unique, median gene expression zone of two different facial development genes early in embryonic development.

Then, researchers took things a step further. They used small-molecule inhibitors to eliminate the activity of the proteins produced by the bird-specific, median signaling zone in chicken embryos. This caused ancestral molecular activity and ancestral anatomy in the chickens. In other words, the scientists created the facial structure that's usually seen in dinosaurs in chickens.

The findings reveal a bit more about the process of evolution in birds. More specifically, it shows that a single, simple developmental mechanism can have wide-ranging effects.

The findings are published in the journal Evolution.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).