Scientists have attempted to turn alligator scales into feathers by inserting genes into the reptiles' eggs, in order to investigate the link between ancient dinosaurs and modern birds.

It is now well established that many dinosaurs had feathers, and some feathered dinosaurs evolved into the birds we see around us today.

Feathers were a useful invention, helping dinosaurs to stay warm, attract mates and, ultimately, fly.

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But the process by which dinosaurs’ reptilian scales turned into feathers remains largely mysterious.

"We now have a potential molecular explanation for these hypothesised missing links," said Dr Cheng-Ming Chuong, a regenerative medicine physician at the University of Southern California.

Like the mythical “flying dragons” of ancient cultures, “maybe we can also make reptiles today grow feathers,” said Dr Chuong.

Besides understanding how feathers are created, Dr Chuong said that his team's work, published in Molecular Biology and Evolution, also has practical applications in medicine.

“Our laboratory try to apply these principles toward skin appendage stem cells to help patients suffered from burn injury to rebuild skin,” he said.

The shared evolutionary history of reptiles and birds means that many of the genetic processes controlling the formation of their bodies are also shared.

This has been demonstrated before when scientists showed genes controlling tooth formation could be switched on in chickens, making them grow teeth.

Dr Chuong and his team wanted to unlock the genetic potential for feathers in scales.

Alligators are descended from the same ancient reptiles as birds, and as evolutionary cousins of modern birds their scaly skin served as a stand in for dinosaurs.

After performing a complete genetic analysis of chickens and alligators as they develop in eggs, the researchers identified key genes involved in feather formation.

They then placed these chicken feather genes in alligator eggs, with the goal of prompting the scales on the growing reptiles’ skin to develop into feathers.

As a result, some of the scales grew into structures “similar to the unusual filamentous appendages found in the fossils of feathered dinosaurs," said Dr Chuong.

The research team located five genetic components that are required for the formation of feathers.

The “feather-like appendages” that emerged from these experiments suggest the components identified are responsible for shaping much of a feather's structure.