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Scientists discover how feathers evolved from reptiles’ scales

Caudipteryx, a feathered dinosaurScientists have re-created the beginnings of the process by which scales evolve into feathers. We now have a greater understanding of how some dinosaurs came to be covered with feathers—small, feathered dinosaurs being the ancestors of birds. A team of researchers led by Professor Cheng-Ming Choung from the University of Southern California identified the feather-forming genes in modern birds, then activated the same ones in alligator embryos. This prompted the alligator scales to change into feathers, in a way that may be similar to how the earliest feathers evolved 150 million years ago. "You can see we can indeed induce them to form appendages. Although [they are] not beautiful feathers, they really try to elongate," Professor Choung explained.

Dinosaurs and birds in Cretaceous China (J. Sibbick)
Caudipteryx fossil with feather impressions (Daderot)
Birds, along with feathered dinosaurs such as Velociraptor and Deinonychus, are ultimately descended from non-feathered dinosaurian ancestors that had scaly skins. Both scales and feathers are made of the same substance, keratin, but exactly how scales evolved into feathers has remained guesswork up until now.
An important clue turned up in 2014, when an unusual feathered dinosaur called Kulindadromeus (which was not a theropod, unlike other feathered dinosaurs) was discovered in Siberia. Some of the feather-like filaments covering its body were shown to be growing out of scales.
Kulindadromeus (Nobu Tamura)
Why did the researchers experiment on alligators? Archosaurs are a group of reptiles that gave rise to dinosaurs, birds and the crocodile family—including alligators. Of the modern reptiles, alligators are the most similar to dinosaurs. Although alligators are not closely related to birds, Professor Choung’s tweaking of their genes still triggered the early stage of the feather-growing process. This demonstrates that the evolution of feathers from scales was quite likely to have happened in reptiles that were birds' close relatives, i.e. dinosaurs.

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