Dinosaur Discovery Reveals Just How Fluffy Bird-like Dinos Were

Michael Brace on Flickr

For more than 150 years, paleontologists have known that dinosaurs had feathers. Now, a new study shows just how fluffy certain dinosaurs really were.

Researchers at the University of Bristol, U.K., examined a particularly well-preserved Anchiornis, a crow-sized dinosaur with four wings. They found that its body feathers, or "contour" feathers, had a distinct shape that no longer exists on birds. These now-extinct feathers had a short quill, with barbs that made the feather forked like a "Y."

The study, published in the journal Paleontology, suggested the unusual shape made the dinosaurs particularly soft and fluffy. This would have helped to keep the warm-blooded creatures warm, but it could also have increased drag while they were flying—the researchers believe this may be the reason birds no longer have the Y-shaped feathers.

A new depiction of Anchoirnis and its contour feather. Rebecca Gelernter

Theropod dinosaurs like the Anchiornis are the ancestors of modern birds, with T. Rex and Velociraptor being their evolutionary cousins. Technically, birds are dinosaurs. There is clear evidence that theropods had feathers and even wings, but knowledge of the feather coverage on many species remains speculative. For instance, it's unclear to what extent T. Rex had feathers.

While you usually can't tell whether or not an animal had feathers just by looking at the fossilized bones, some detailed fossils of dinosaurs do include imprints of feathers. The most famous example of a fossil showing teeth, claws, a tail and clearly formed feathers is Archaeopteryx Lithographica. This small, winged dinosaur's name means "ancient wing from the printing stone."

Fossil feather comparison: novel form versus modern form. University of Bristol

Anchiornis fossils are exceptionally well-preserved, and scientists could even tell, remarkably, that they were colored black and white with a red tuft of head feathers. They also had a second set of wings on their back legs, possibly to help direct them while gliding.

Some of the feathers the researchers studied had fallen off the body in the decaying process, so it was easier for them to see the individual feathers imprinted on the stone. From other fossils, they were able to tell the general shape that the feathers took around the body.

To accompany this study, a paleo-artist re-imagined the dinosaur in the most up-to-date way possible, with an extra-fluffy body, like a chick. The animal also had large feathers on its wings that looked more like those on modern birds. With this information, plus the size, shape, and color of the animal, the new artistic rendering is the most scientifically accurate drawing of the bird to date.

Microraptor, a dinosaur with clear feathers related to Anchiornis photographed at the Academy of Natural Sciences at Drexel University. Kristin Hugo / Strange Biology