Xu, X., Clark, J. M., Mo, J., Choiniere, J., Forster, C. A., Erickson, G. M., Hone, D. W. E., Sullivan, C., Eberth, D. A., Nesbitt, S., Zhao, Q., Hernandez, R., Jia, C., Han, F. & Guo, Y. 2009. A Jurassic ceratosaur from China helps clarify avian digital homologies. Nature, 459: 940–944.