Chinese fossil find shows birds shed their dinosaur tails step by step
A Jurassic fossil dating back 150 million years fills in a vital part of the evolutionary puzzle of how birds took to the skies

“The evolutionary assembly of the flight-adapted bird body plan encompasses some of the most profound morphological changes in terrestrial vertebrate history,” a team of Chinese researchers said in their paper published in the peer-reviewed journal Science Advances on July 1.
Unlike most non-avian dinosaurs, modern birds have a pygostyle, which is a skeletal structure formed by the fusion of the final few caudal or tail vertebrae. This short tail structure acts as an anchor for tail feathers and muscles.
But studying the transformation to this more aerodynamically favourable structure has been difficult, due to the “exceeding rarity” of early-diverging birds and birdlike dinosaurs.