Integumentary Structures in Kulindadromeus zabaikalicus, a Basal Neornithischian Dinosaur from the Jurassic of Siberia

Recent studies on the origin of feathers have been stimulated by discoveries of feather-like structures in various nonavian theropod dinosaurs from Late Jurassic to Early Cretaceous deposits in northeastern China. Filamentous integumentary structures are also known in two ornithischian dinosaurs from China, but whether these filaments form part of the evolutionary lineage of feathers has been controversial. Kulindadromeus zabaikalicus, a basal neornithischian dinosaur from the Jurassic of Siberia, preserves diverse integumentary structures, including monofilaments, more complex protofeather structures and scales on its tail and distal parts of its limbs. These exceptionally preserved specimens suggest that integumental features were diversified even in ornithischian dinosaurs and that “protofeather”-like structures were potentially widespread among the entire dinosaur clade.