When this dinosaur was discovered, it rapidly rose to the fourth position in my favorite list - and it’s obvious why. This dinosaur proves pretty clearly that feathers were synapomorphic for both Ornithischia and Saurischia (something I have been suggesting for years due to quills being found on another basal ornithischian, Tianyulong, as well as protofeathers found on Psittacosaurus, and the presence of feather protein genes in the crocodile genome, suggesting that protofeather-esque filaments are a trait of all of archosauria, based on cladistics. Genomes, man. Genomes.) It was found in the Ukureyskaya formation in Russia, which dates back to the middle to late Jurassic, about 169 to 144 million years ago in the Bajocian to Tithonian ages. It is known from a partial skeleton in rock that lead to amazing preservation of both feathers and scales. Now, this fossil was stolen and described as another species, Kulindapteryx, but this is not valid and should be ignored (curse you, BANDits.)
Kulindadromeus was a bipedal runner, about 1.5 meters long, with a short head, short forelimbs, and long hindlimbs and tail. It had scales on the top of its tale and scales branching into feather like structures on the main part of the body. This fuzz all over the body are hair like filaments like stage 1 dino fuzz on Sinosauropteryx, and then another type is longer filaments on the upper arms and thighs like type three feathers, and then unique bundles of ribbon like structures on the upper lower legs that are made from parallel filaments.
Kulindadromeus also had three types of scales: overlapping hexagonal scales on the lower shins, non-overlapping scales on the hands ankles and feet, and arched rectangular scales on the tail, forming rows.
According to the science of evolutionary cladistics, the closer two clades are related to one another, the more likely any features shared by those clades was only evolved once, in their last common ancestor. More deviated groups - such as birds and bats - that share a feature evolved them separately. As such, the fact that crocodiles have a dormant feather gene (same protein) implies that the last common ancestor of both crocodiles and birds had feathers - and that’s just from genomics.
Now, while this feature may have been lost in many archosaurian species - as fur is lost in many species of mammals - it is important that we now, as paleontologists, switch our line of thought from “scaled until proven otherwise,” to “feathered until proven otherwise.” The discovery of so many feathered or quilled theropods - as well as quite a few quilled and feathered ornithischians, now - only bolsters that claim. This is by far one of the most exciting discoveries of modern paleontology, and I can’t wait to see what more we find out about the connection between dinosaurs, birds, and feathers in the coming years.