Pterosaurs
were the first vertebrates to achieve true flapping flight, but in the
absence of living representatives, many questions concerning their
biology and lifestyle remain unresolved. Pycnofibres—the integumentary
coverings of pterosaurs—are particularly enigmatic: although many
reconstructions depict fur-like coverings composed of pycnofibres, their
affinities and function are not fully understood.
Here, we report the
preservation in two anurognathid pterosaur specimens of morphologically
diverse pycnofibres that show diagnostic features of feathers, including
non-vaned grouped filaments and bilaterally branched filaments,
hitherto considered unique to maniraptoran dinosaurs, and preserved
melanosomes with diverse geometries. These findings could imply that
feathers had deep evolutionary origins in ancestral archosaurs, or that
these structures arose independently in pterosaurs. The presence of
feather-like structures suggests that anurognathids, and potentially
other pterosaurs, possessed a dense filamentous covering that probably
functioned in thermoregulation, tactile sensing, signalling and
aerodynamics.
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We
thank Q. Ji, S. Ji and H. Huang for access to the specimen CAGS–Z070,
as well as S. C. Kohn, Y. Fang, C. Wang and T. He for laboratory
assistance. This work was supported by the National Natural Science
Foundation of China (41672010 and 41688103) and Strategic Priority
Research Program (B) of the Chinese Academy of Sciences (XDB26000000) to
B.J., Research Grant Council of Hong Kong-General Research Fund
(17103315) to M.P., ERC-StG-2014-637691-ANICOLEVO to M.E.M. and Natural
Environment Research Council Standard Grant NE/1027630/1 to M.J.B.
Author information
Affiliations
Center
for Research and Education on Biological Evolution and Environments,
School of Earth Sciences and Engineering, Nanjing University, Nanjing,
China
Zixiao Yang
& Baoyu Jiang
School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
Maria E. McNamara
Department of Earth Sciences, University of Bristol, Bristol, UK
Stuart L. Kearns
& Michael J. Benton
Vertebrate Palaeontology Laboratory, Department of Earth Sciences, University of Hong Kong, Pokfulam, China
Michael Pittman
Foundation for Scientific Advancement, Sierra Vista, AZ, USA
Thomas G. Kaye
UCD School of Earth Sciences, University College Dublin, Dublin, Ireland
Patrick J. Orr
Key
Laboratory of Vertebrate Evolution and Human Origins, Institute of
Vertebrate Paleontology and Paleoanthropology, Chinese Academy of
Sciences, Beijing, China
Xing Xu
Contributions
B.J.
and M.J.B. designed the research. Z.Y., B.J. and X.X. systematically
studied the specimens. Z.Y., S.L.K., M.E.M. and P.J.O. performed the SEM
analysis. Z.Y. and B.J. performed the FTIR analysis. M.P. and T.G.K.
performed the laser-stimulated fluorescence imaging, data reduction and
interpretation. M.J.B. performed the maximum-likelihood analyses. Z.Y.,
B.J., M.J.B., M.E.M., X.X. and P.J.O. wrote the paper. All authors
approved the final draft of the paper.
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