• 2.
    Norberg, U. Vertebrate Flight: Mechanics, Physiology, Morphology, Ecology and Evolution (Springer, Berlin, 1990).
  • 3.
    Xu, X. et al. An integrative approach to understanding bird origins. Science 346, 1253293 (2014).
  • 4.
    Gatesy, S. M. & Middleton, K. M. Bipedalism, flight, and the evolution of theropod locomotor diversity. J. Vertebr. Paleontol. 17, 308–329 (1997).
  • 5.
    Chatterjee, S. & Templin, R. J. Biplane wing planform and flight performance of the feathered dinosaur Microraptor gui. Proc. Natl Acad. Sci. USA 104, 1576–1580 (2007).
  • 6.
    Xu, X. et al. A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings. Nature 521, 70–73 (2015).
  • 7.
    Padian, K. Dinosaur up in the air. Nature 521, 40–41 (2015).
  • 8.
    Liu, Y., Liu, Y., Ji, S. A. & Yang, Z. U–Pb zircon age for the Daohugou Biota at Ningcheng of Inner Mongolia and comments on related issues. Chin. Sci. Bull. 51, 2634–2644 (2006).
  • 9.
    Huang, D. Yanliao biota and Yanshan movement (in Chinese). Acta Palaeontologica Sin. 54, 501–546 (2015).
  • 10.
    Campione, N. E., Evans, D. C., Brown, C. M. & Carrano, M. T. Body mass estimation in non-avian bipeds using a theoretical conversion to quadruped stylopodial proportions. Methods Ecol. Evol. 5, 913–923 (2014).
  • 11.
    Persons, W. S., Currie, P. J. & Norell, M. A. Oviraptorosaur tail forms and functions. Acta Palaeontol. Pol. 59, 553–567 (2013).
  • 12.
    O’Connor, J. K. & Sullivan, C. Reinterpretation of the Early Cretaceous maniraptoran (Dinosauria: Theropoda) Zhongornis haoae as a scansoriopterygid-like non-avian, and morphological resemblances between scansoriopterygids and basal oviraptorosaurs. Vertebr. Palasiat. 52, 3–30 (2014).
  • 13.
    Gatesy, S. M. & Thomason, J. in Functional Morphology in Vertebrate Paleontology (ed. Thomason, J. J.) 219–234 (Cambridge Univ. Press, Cambridge, 1995).
  • 14.
    Zhang, F., Zhou, Z., Xu, X., Wang, X. & Sullivan, C. A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers. Nature 455, 1105–1108 (2008).
  • 15.
    Zhang, F., Zhou, Z., Xu, X. & Wang, X. A juvenile coelurosaurian theropod from China indicates arboreal habits. Naturwissenschaften 89, 394–398 (2002).
  • 16.
    Turner, A. H., Makovicky, P. J. & Norell, M. A. A review of dromaeosaurid systematics and paravian phylogeny. Bull. Am. Mus. Nat. Hist. 371, 1–206 (2012).
  • 17.
    Xu, X. et al. A new feathered maniraptoran dinosaur fossil that fills a morphological gap in avian origin. Chin. Sci. Bull. 54, 430–435 (2009).
  • 18.
    Balanoff, A. M. & Norell, M. A. Osteology of Khaan mckennai (Oviraptorosauria: Theropoda). Bull. Am. Mus. Nat. Hist. 372, 1–77 (2012).
  • 19.
    Hutchinson, J. R. The evolution of pelvic osteology and soft tissues on the line to extant birds (Neornithes). Zool. J. Linn. Soc. 131, 123–168 (2001).
  • 20.
    Zhang, F. et al. Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds. Nature 463, 1075–1078 (2010).
  • 21.
    Thorington, J. R. W., Darrow, K. & Anderson, C. G. Wing tip anatomy and aerodynamics in flying squirrels. J. Mamm. 79, 245–250 (1998).
  • 22.
    Oshida, T., Hiraga, H., Nojima, T. & Yoshida, M. C. Anatomical and histological notes on the origin of the long accessory styliform cartilage of the Russian flying squirrel, Pteromys volans orii. Mammal Study 25, 41–48 (2000).
  • 23.
    Dial, K. P. Wing-assisted incline running and the evolution of flight. Science 299, 402–404 (2003).
  • 24.
    Lovette, I. J. & Fitzpatrick, J. W. Handbook of Bird Biology 3rd edn (John Wiley & Sons, Hoboken, 2016).
  • 25.
    Sullivan, C. et al. The vertebrates of the Jurassic Daohugou biota of northeastern China. J. Vertebr. Paleontol. 34, 243–280 (2014).
  • 26.
    Liu, Y., Liu, Y. & Zhang, H. LA-ICPMS zircon U-Pb dating in the Jurassic Daohugou beds and correlative strata in Ningcheng of Inner Mongolia. Acta Geol. Sin. 80, 733–742 (2006).
  • 27.
    Liu, Y.-Q. et al. Timing of the earliest known feathered dinosaurs and transitional pterosaurs older than the Jehol biota. Palaeogeogr. Palaeoclimatol. Palaeoecol. 323–325, 1–12 (2012).
  • 28.
    Chu, Z. et al. High-precision U-Pb geochronology of the Jurassic Yanliao biota from Jianchang (western Liaoning Province, China): age constraints on the rise of feathered dinosaurs and eutherian mammals. Geochem. Geophys. Geosyst. 17, 3983–3992 (2016).
  • 29.
    Xu, X., Zhou, Z., Sullivan, C., Wang, Y. & Ren, D. An updated review of the Middle–Late Jurassic Yanliao Biota: chronology, taphonomy, paleontology and paleoecology. Acta Geol. Sin. 90, 2229–2243 (2016).
  • 30.
    Benson, R. B. J. et al. Rates of dinosaur body mass evolution indicate 170 million years of sustained ecological innovation on the avian stem lineage. PLoS Biol. 12, e1001853 (2014).
  • 31.
    Christiansen, P. & Fariña, R. A. Mass prediction in theropod dinosaurs. Hist. Biol. 16, 85–92 (2004).
  • 32.
    Serrano, F. J., Palmqvist, P. & Sanz, J. L. Multivariate analysis of neognath skeletal measurements: implications for body mass estimation in Mesozoic birds. Zool. J. Linn. Soc. 173, 929–955 (2015).
  • 33.
    Campione, N. E. & Evans, D. C. A universal scaling relationship between body mass and proximal limb bone dimensions in quadrupedal terrestrial tetrapods. BMC Biol. 10, 60 (2012).
  • 34.
    Goloboff, P. A. & Catalano, S. A. TNT version 1.5, including a full implementation of phylogenetic morphometrics. Cladistics 32, 221–238 (2016).
  • 35.
    Brusatte, S. L. in Computational Paleontology (ed. Elewa, A. M. T.) 53–74 (Springer, Heidelberg, 2011).
  • 36.
    Laurin, M. The evolution of body size, Cope’s rule and the origin of amniotes. Syst. Biol. 53, 594–622 (2004).
  • 37.
    Wang, M. & Lloyd, G. T. Rates of morphological evolution are heterogeneous in Early Cretaceous birds. Proc. R. Soc. Lond. B 283, 20160214 (2016).
  • 38.
    Bapst, D. W. paleotree: an R package for paleontological and phylogenetic analyses of evolution. Methods Ecol. Evol. 3, 803–807 (2012).
  • 39.
    Revell, L. J. Size-correction and principal components for interspecific comparative studies. Evolution 63, 3258–3268 (2009).
  • 40.
    Benson, R. B. J. & Choiniere, J. N. Rates of dinosaur limb evolution provide evidence for exceptional radiation in Mesozoic birds. Proc. R. Soc. Lond. B 280, 20131780 (2013).
  • 41.
    Hu, D. et al. A bony-crested Jurassic dinosaur with evidence of iridescent plumage highlights complexity in early paravian evolution. Nat. Commun. 9, 217 (2018).
  • 42.
    Paradis, E., Claude, J. & Strimmer, K. APE: analyses of phylogenetics and evolution in R language. Bioinformatics. 20, 289–290 (2004).
  • 43.
    Felsenstein, J. Phylogenies and the comparative method. Am. Nat. 125, 1–15 (1985).
  • 44.
    Revell, L. J. phytools: an R package for phylogenetic comparative biology (and other things). Methods Ecol. Evol. 3, 217–223 (2012).
  • Acknowledgements

    We thank S.-X. Jiang, D.-Y. Huang, Y.-H. Pan and Z.-Q. Yu for discussion, Q.-R. Meng for help in the field, T. Zhao for taking scanning electron microscopy photographs, D.-H. Li for specimen preparation and W. Gao for photographing. This research was supported by the National Natural Science Foundation of China (41688103; 41722202), Youth Innovation Promotion Association CAS (2016073) and the State Key Laboratory of Lithospheric Evolution (Z201604).

    Reviewer information

    Nature thanks Thomas Richard Holtz, Peter Makovicky and Kevin Padian for their contribution to the peer review of this work.

    Author information

    Affiliations

    1. Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China

      • Min Wang
      • , Jingmai K. O’Connor
      • , Xing Xu
      •  & Zhonghe Zhou
    2. Center for Excellence in Life and Paleoenvironment, Chinese Academy of Science, Beijing, China

      • Min Wang
      • , Jingmai K. O’Connor
      • , Xing Xu
      •  & Zhonghe Zhou

    Contributions

    Z.Z. and M.W. designed the research project; Z.Z. and M.W. conducted the fieldwork; M.W. performed the phylogenetic, histological and phylogenetic principal component analyses; and M.W., J.K.O., X.X. and Z.Z. wrote the manuscript.

    Competing interests

    The authors declare no competing interests.

    Corresponding author

    Correspondence to Min Wang.

    Extended data figures and tables

    1. Extended Data Fig. 1 Additional photographs of Ambopteryx, IVPP V24192.

      a, Counter slab. b, Skeletal reconstruction based on preserved bones. c, Skull. d, Gastroliths and the unidentified bony stomach content. Abbreviations as in Fig. 1, except for: fe, feather associated with the neck; lil, left ilium;; lti, left tibia; pd, pedal digits; and ub, unidentified bony element. The white box indicates the position from which the sample was taken for histological analysis. Scale bars, 10 mm (a, c, d), 20 mm (b).
    2. Extended Data Fig. 2 Bone histology of Ambopteryx.

      ad, Thin cross-section of the left humerus (a, b) and the unidentified bony stomach content (c, d). The arrowheads indicate the osteocyte lacunae. Scale bars, 100 μm (a–c), 200 μm (d).
    3. Extended Data Fig. 3 Anatomy of Ambopteryx, IVPP V24192.

      ad, Interpretative drawings of the neck and pectoral girdle (a), caudal vertebrae and pygostyle (b), left forelimb (c) and pelvis and left hindlimb (d). Abbreviations as in Figs. 1, 2, except for: ca, caudal vertebrae; cm, calcaneum; de, deltopectoral crest of humerus; do, dorsal vertebrae; I–III, metacarpals I–III; ip, iliac peduncle of ilium; mtII–IV, metatarsals II–IV; p1–4, pedal digits I to IV; and st, styliform element. Scale bars, 10 mm (ad).
    4. Extended Data Fig. 4 Forelimb comparisons between Ambopteryx and Yi.

      a, Left forelimb of Ambopteryx (IVPP V24192). bd, Left forelimb (b), right humerus (c) and the right styliform element (d) of Yi (STM 31-2). The proximal margins of the humeri are marked in white dashed lines to show the differences between these two taxa. Abbreviations as in Figs. 1, 2, except for: st, styliform element. Scale bars, 10 mm (a), 20 mm (bd).
    5. Extended Data Fig. 5 Comparisons of hand morphology among Scansoriopterygidae.

      ac, Line drawings of the hands of Ambopteryx (a), Epidendrosaurus (b) and Yi (c). Scale bars, 10 mm (a, b), 20 mm (c).
    6. Extended Data Fig. 6 Scanning electron microscopy photographs of the soft tissues that are preserved in Ambopteryx.

      ad, Feather samples associated with the neck. ef, Samples of membranous tissues taken from the area between the left femur and left manual digits. Arrows denote the positions of the samples. Scale bars, 2 μm.
    7. Extended Data Fig. 7 Time-scaled recovered strict-consensus tree of Mesozoic coelurosaurians.

      Bremer and bootstrap values are labelled near the corresponding node in bold italic and upright non-bold font, respectively.
    8. Extended Data Fig. 8 Compiled super-tree of the sampled Mesozoic coelurosaurians used in morphometric analyses.

      Complete tree for the coelurosaurians used in generating the PPCA morphospaces shown in Fig. 3b, c.

    Supplementary information

    1. Supplementary Information

      This file contains Supplementary Text Sections 1–5; which include additional anatomical description, stomach contents and diet of Ambopteryx longibrachium, Supplementary Tables 1, 2, 4 and 5, and the data used in the phylogenetic analysis.
    2. Reporting Summary

    3. Supplementary Table 3

      This file contains appendicular limb bone measurements of Mesozoic coelurosaurians used in the phylogenetic principal components analysis.