title: A Feathered Dinosaur Tail with Primitive Plumage Trapped in Mid-Cretaceous Amber.
abstract: In the two decades since the discovery of feathered dinosaurs [1-3], the range of plumage known from non-avialan theropods has expanded significantly, confirming several features predicted by developmentally informed models of feather evolution [4-10]. However, three-dimensional feather morphology and evolutionary patterns remain difficult to interpret, due to compression in sedimentary rocks [9, 11]. Recent discoveries in Cretaceous amber from Canada, France, Japan, Lebanon, Myanmar, and the United States [12-18] reveal much finer levels of structural detail, but taxonomic placement is uncertain because plumage is rarely associated with identifiable skeletal material [14]. Here we describe the feathered tail of a non-avialan theropod preserved in mid-Cretaceous (∼99 Ma) amber from Kachin State, Myanmar [17], with plumage structure that directly informs the evolutionary developmental pathway of feathers. This specimen provides an opportunity to document pristine feathers in direct association with a putative juvenile coelurosaur, preserving fine morphological details, including the spatial arrangement of follicles and feathers on the body, and micrometer-scale features of the plumage. Many feathers exhibit a short, slender rachis with alternating barbs and a uniform series of contiguous barbules, supporting the developmental hypothesis that barbs already possessed barbules when they fused to form the rachis [19]. Beneath the feathers, carbonized soft tissues offer a glimpse of preservational potential and history for the inclusion; abundant Fe2+suggests that vestiges of primary hemoglobin and ferritin remain trapped within the tail. The new finding highlights the unique preservation potential of amber for understanding the morphology and evolution of coelurosaurian integumentary structures.
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China; School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China. Electronic address: xinglida@gmail.com.
authors.forename: Lida
authors.initials: L
authors.lastname: Xing
authors.affiliation: Royal Saskatchewan Museum, Regina, Saskatchewan S4P 4W7, Canada; Biology Department, University of Regina, Regina, Saskatchewan S4S 0A2, Canada. Electronic address: ryan.mckellar@gov.sk.ca.
authors.forename: Ryan C
authors.initials: RC
authors.lastname: McKellar
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Xu
authors.affiliation: Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Science, Beijing 100049, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.affiliation: Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Bai
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
authors.forename: W Scott
authors.initials: WS
authors.lastname: Persons
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
authors.forename: Tetsuto
authors.initials: T
authors.lastname: Miyashita
authors.affiliation: School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Benton
authors.affiliation: School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Wolfe
authors.affiliation: Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Science, Beijing 100049, China.
authors.forename: Qiru
authors.initials: Q
authors.lastname: Yi
authors.affiliation: Department of Exercise and Health Science, University of Taipei, Taipei 11153, China; Department of Geology, Chinese Culture University, Taipei 11114, China.
authors.forename: Kuowei
authors.initials: K
authors.lastname: Tseng
authors.affiliation: Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, Ministry of Education, Guilin 541004, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Ran
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Currie
mesh_terms: D018647:Amber; D000818:Animals; D005075:Biological Evolution; D025061:Dinosaurs / Q000033:anatomy & histology*; D005241:Feathers; D005580:Fossils
chemical_list: D018647:Amber
keywords: Burmese amber; Cenomanian; Coelurosauria; feather evolution