title: Mummified precocial bird wings in mid-Cretaceous Burmese amber.
abstract: Our knowledge of Cretaceous plumage is limited by the fossil record itself: compression fossils surrounding skeletons lack the finest morphological details and seldom preserve visible traces of colour, while discoveries in amber have been disassociated from their source animals. Here we report the osteology, plumage and pterylosis of two exceptionally preserved theropod wings from Burmese amber, with vestiges of soft tissues. The extremely small size and osteological development of the wings, combined with their digit proportions, strongly suggests that the remains represent precocial hatchlings of enantiornithine birds. These specimens demonstrate that the plumage types associated with modern birds were present within single individuals of Enantiornithes by the Cenomanian (99 million years ago), providing insights into plumage arrangement and microstructure alongside immature skeletal remains. This finding brings new detail to our understanding of infrequently preserved juveniles, including the first concrete examples of follicles, feather tracts and apteria in Cretaceous avialans.
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.
authors.forename: Lida
authors.identifier: http://orcid.org/0000-0003-3923-9206
authors.initials: L
authors.lastname: Xing
authors.affiliation: Palaeontology, Royal Saskatchewan Museum, Regina, Saskatchewan, Canada S4P 2V7.|Biology Department, University of Regina, Regina, Saskatchewan, Canada S4S 0A2.
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: Min
authors.identifier: http://orcid.org/0000-0001-8506-1213
authors.initials: M
authors.lastname: Wang
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: Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China.
authors.forename: Jingmai K
authors.initials: JK
authors.lastname: O'Connor
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: Institute of Geology and Paleontology, Linyi University, Linyi 276000, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Exercise and Health Science, University of Taipei, Taipei 11153, China.
authors.forename: Kuowei
authors.initials: K
authors.lastname: Tseng
authors.affiliation: Dinosaur Tracks Museum, University of Colorado Denver, Denver, Colorado 80217, USA.
authors.forename: Martin G
authors.initials: MG
authors.lastname: Lockley
authors.affiliation: Institute of High Energy Physics, Chinese Academy of Science, Beijing 100049, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.forename: Weiwei
authors.initials: W
authors.lastname: Zhang
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
mesh_terms: D018647:Amber; D000818:Animals; D001717:Birds; D005241:Feathers; D005580:Fossils; D010858:Pigmentation; D014921:Wings, Animal
chemical_list: D018647:Amber