In today's Science: http://www.sciencemag.org/cgi/content/full/306/5696/653 Zhou, Z., & F. Zhang. 2004. A precocial avian embryo from the lower Cretaceous of China. Science 306 (5696): 653. Precocial because it has a full down covering. It's an enantiornithine. Cheers, Christopher Taylor