1. Swisher, C. C. et al. A Cretaceous age for the feathered dinosaurs of Liaoning, China. Nature 400, 58–61 (1999)
2. He, H. Y. et al. Timing of the Jiufotang Formation (Jehol Group) in Liaoning, northeastern China, and its implications. Geophys. Res. Lett. 31, 1–4 (2004)
3. Chang, M., Chen, P. J., Wang, Y. Q. & Wang, Y. (eds) The Jehol Biota (Shanghai Sci. and Technol. Publishers, Shanghai, 2003)
4. Zhou, Z. H., Barrett, P. M. & Hilton, J. An exceptionally preserved Lower Cretaceous ecosystem. Nature 421, 807–814 (2003)
5. Wellnhofer, P. The Illustrated Encyclopedia of Pterosaurs (Salamander Books, London, 1991)