Zhongornis haoae is an itty-bitty, teeny-weeny juvenile bird from the Early Cretaceous of China. At just over 10 centimeters long, the little guy is positively tiny. The drawing above is a measured one: every piece of the body was drawn according to its length as described in the description. Zhongornis is unique for a number of reasons. First and foremost, its tail is transitional between the long bony tails of Archaeopteryx and Jeholornis and the short lil' pygostyles of the...Pygostylia. Zhongornis has 13 short 'n' stumpy caudal vertebrae which anchored a lengthy tail fan. Additionally, Zhongornis' third manual digit is made up of only three phalanxes, making Zhongornis unique among known birds, both living and extinct.
The skull is badly crushed, so whether the little bird had teeth or not is unknown. I decided to give it a short little beak instead--maybe its teeth grew in later. Gao, et al. (the describers) suggest that Zhongornis' reduced third finger is also in line with the transition from outgroup birds to modern forms, but that can't be true. If Zhongornis is intermediate between long-tailed birds and Pygostylia, one would expect to see confuciusornid birds with just three phalanxes in their third manual digit, but in fact they retain all four. So Zhongornis developed that particular mutation by itself. If anybody would like a copy of the paper, I have it in PDF form, so let me know and I'll send it your way.
Gao, C., Chiappe, L. M., MEng, Q., O'Connor, J. K., Wang, X., Cheng, X. & Liu, J. (2008). A new basal lineage of Early Cretaceous birds from China and its implications on the evolution of the avian tail. Palaeontology 51(4): 775-791.