Dr Pascal Godefroit, a paleontologist with the Royal Belgian Institute of Natural Sciences in Brussels, and his colleagues have discovered the fossilized remains of a feathered plant-eating dinosaur that lived in the lake-dotted lowlands of Jurassic Siberia, between 169 and 144 million years ago. Previously only carnivorous dinosaurs were known to have had feathers so this new species indicates that all dinosaurs could have been feathered.

The new dinosaur, named Kulindadromeus zabaikalicus, was a small plant-eater, only about 1 meter long. It had long hind legs and short arms, with five strong fingers.

Its snout was short, and its teeth show clear adaptations to plant eating.

In evolutionary terms, it sits low in the evolutionary tree of ornithischian dinosaurs.

Six skulls and several hundred partial skeletons of Kulindadromeus zabaikalicus were recovered from the Kulinda fossil site – the lower part of the Ukurey Formation in eastern Siberia.

According to a paper published in the journal Science, Kulindadromeus zabaikalicus had scales on its tail and shins, and short bristles on its head and back. It also had complex, compound feathers on its arms and legs.

“I was really amazed when I saw this,” Dr Godefroit said.

“We knew that some of the plant-eating ornithischian dinosaurs had simple bristles, and we couldn’t be sure whether these were the same kinds of structures as bird and theropod feathers.”

“Our new find clinches it: all dinosaurs had feathers, or at least the potential to sprout feathers.”

“These feathers are really very well preserved,” added Dr Maria McNamara of University College Cork, a co-author on the discovery.

“We can see each filament and how they are joined together at the base, making a compound structure of six or seven filaments, each up to 1.5 cm long.”

This discovery suggests that feather-like structures were likely widespread in dinosaurs, possibly even in the earliest members of the group.

Feathers probably arose during the Triassic, more than 220 million years ago, for insulation and signaling, and were only later used for flight.

Smaller dinosaurs were probably covered in feathers, mostly with colorful patterns, and feathers may have been lost as dinosaurs grew up and became larger.

“Developmental experiments in modern chickens suggest that avian scales are aborted feathers, an idea that explains why birds have scaly legs,” said co-author Prof Danielle Dhouailly of the Université Joseph Fourier in Grenoble, France.

“The astonishing discovery is that the molecular mechanisms needed for this switch might have been so clearly related to the appearance of the first feathers in the earliest dinosaurs.”

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Pascal Godefroit et al. 2014. A Jurassic ornithischian dinosaur from Siberia with both feathers and scales. Science, vol. 345, no. 6195, pp. 451-455; doi: 10.1126/science.1253351