Science 29 January 2010:
Vol. 327. no. 5965, pp. 571 - 574
A Basal Alvarezsauroid Theropod from the Early Late Jurassic of Xinjiang, China
J. N. Choiniere et al.
The Alvarezsauroidea group extends the clade containing birds and their theropod relatives back to 160 million years ago.