Over 30 species of non-avian dinosaurs have been confirmed to have feathers, either from direct fossilized evidence of feathers, or other indicators, such as quill knobs. Up until now, all of those dinosaurs were confirmed to be carnivorous theropods, like Velociraptor and the ancestors of birds. However, fossilized remains of a new type of herbivorous dinosaur indicate that all dinosaurs may have had feathers. The study was led by Pascal Godefroit from the Royal Belgian Institute of Natural History in Brussels and the results were published in Science.
The fossils were discovered at the Kulinda site in Siberia, along the banks of the Olov River. The new species, Kulindadromeus zabaikalicus, was discovered in 2013 and preliminary K-Ar testing estimates that the species lived about 169-150 million years ago. It was approximately 3 meters long, which is relatively small for a dinosaur. The bipedal animal had short forelimbs and longer hind legs with five digits. The description was made based on hundreds of incomplete skeletons, including six skulls.
The fact that the skeletons were not found intact could indicate that while the dinosaurs were alive, that environment had rivers. Upon the dinosaur’s death, the water likely transported the animal, causing portions of the skeleton to disassociate. These particular individuals were likely covered by sediment on the bottom of the river, protecting the carcass from scavengers, and allowing imprints from the feathers and scales to be preserved.
"I was really amazed when I saw this,” Godefroit stated in a press release. “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.”
The fossilized feathers were sent to specialists who had previous experience with dinosaur feathers. The feathers discovered at the Kulinda site were in remarkable condition, allowing the experts to determine that the feathers were composed of filaments that connected at the base, rather than along a central shaft, like is seen in many modern birds.
"Developmental experiments in modern chickens suggest that avian scales are aborted feathers, an idea that explains why birds have scaly legs,” co-author Danielle Dhouailly added. “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.”
The researchers suspect that feathers were a common feature among dinosaurs, particularly smaller ones. They were likely used to insulate the animals, and evolved to aid in flight much later. Fossils have shown evidence of feathered dinosaurs over a 50 million year timespan, and it is possible that they first appeared 220 million years ago in the Triassic. Of course, it is a bit speculative to assume that every dinosaur could have had feathers, and a great deal of research will be needed to fully explore the prevalence of feathers among dinosaurs.