From dinosaur to bird: How did the transformation take place?

[I]n Bavaria, the Jurassic-aged limestone deposits yielded a near-perfect fossil of Archaeopteryx. It had blade-like serrated teeth and many other features across the skeleton and skull that showed it was a carnivorous dinosaur. But the crow-sized specimen was covered in the impressions of bird-like feathers. For [Thomas] Huxley, this was the transitional form he was seeking: a dinosaur on its way to becoming a bird.

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[I]t was feathers that provided the final incontrovertible evidence that birds evolved from dinosaurs.

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Since then, a spectacular array of small, feathered dinosaurs have been recovered from Liaoning and a few other sites around the world, which plot every conceivable evolutionary step from small fuzz-covered, meat-eating theropods through to fully feathered and winged birds.

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Beginning as simple downy filaments, they had probably originated to keep theropods warm – evidence supporting the theory that at least some dinosaurs were ‘warm-blooded’. They may also have served as ornaments. Festooned with arm feathers, smaller theropods’ plumage would have given them a degree of lift to chase flying insects.

This set of features – small with lightweight bones, rotated shoulder sockets with a furcula, turbocharged breathing systems and feathers – developed in theropods long before they took to the air and set the scene for protobirds.

Read full, original post: The feathered revolution: How dinosaurs became birds