filamentous and unbranched feathers in its holotype specimen. Only the distal ends of the feather impressions are visible and based on their morphology the feathers are considered to be EBFFs, bearing resemblance to those found along the specimens of Beipiaosaurus. These findings suggest that they might have been used for visual display and were common among early therizinosaurs. An evo-devo study published in the year 2003 defined what is a feather. It's stated that the integumentary structures of Beipiaosaurus weren't true feathers, those integumentary structures are filaments that are related to feathers. Classification The affinities of therizinosaurs were originally obscure and often problematic, giving rise to taxonomic debate since they feature similar adaptations to the unrelated sauropodomorphs and ornithischians. The description of Beipiaosaurus helped to assemble the definitive placement of therizinosaurs within the Theropoda, especially as maniraptorans thanks to the numerous theropod features and irrefutable feather impressions in the holotype. Beipiaosaurus was first assigned to the Therizinosauroidea, in a very primitive position by Xu et al. 1999. All subsequent phylogenetic analyses have confirmed this assignment. According to the definition by Paul Sereno of this group, Beipiaosaurus is even by definition the basal most member. Lindsay E. Zanno noted that Beipiaosaurus shares a sister-taxon relationship with Falcarius, a taxon that includes all the more derived therizinosauroids, however, it appears to be that Falcarius is more primitive than Beipiaosaurus. The cladogram below is the result of the performed phylogenetic analysis of the Therizinosauria by Hartman et al. 2019 which is largely based on the data provided by the revision of Zanno in 2010. Beipiaosaurus occupied a more derived position than Falcarius, as previously indicated by Zanno: Paleobiology In 2018, McNamara and colleagues discovered the fossilised remains of skin flakes from numerous feathered dinosaurs from the Jehol Biota and some bird species using scanning electron microscope on the preserved feather impressions. The analyzed fossil taxa consisted of Confuciusornis, Beipiaosaurus, Microraptor and Sinornithosaurus. For Beipiaosaurus, the specimen STM 31-1 was analyzed. By exposing the skin flakes under an electron microscope they found corneocytes, which are cells rich in keratin. In order to make comparisons with extant feathered dinosaurs, they analyzed several bird taxa such as Anas, Lonchura and Taeniopygia and found similar cell structures, but the fossil dinosaur corneocytes were more densely packed with keratin and lacking lipids (fat), suggesting that Beipiaosaurus and co-analyzed taxa did not get as warm as modern birds, mainly