Birds are the direct descendants of a group of feathered, carnivorous dinosaurs that, along with true birds, are referred to as paravians – examples of which include the infamous Velociraptor.
Researchers examined, at high resolution, an exceptionally-preserved fossil of the crow-sized paravian dinosaur Anchiornis – comparing its fossilised feathers to those of other dinosaurs and extinct birds.
The feathers around the body of Anchiornis, known as contour feathers, revealed a newly-described, extinct, primitive feather form consisting of a short quill with long, independent, flexible barbs erupting from the quill at low angles to form two vanes and a forked feather shape.
The observations were made possible by decay processes that separated some of these feathers from the body prior to burial and fossilisation, making their structure easier to interpret.
Such feathers would have given Anchiornis a fluffy appearance relative to the streamlined bodies of modern flying birds, whose feathers have tightly-zipped vanes forming continuous surfaces. Anchiornis’s unzipped feathers might have affected the animal’s ability to control its temperature and repel water, possibly being less effective than the vanes of most modern feathers. This shaggy plumage would also have increased drag when Anchiornis glided.
