ScienceDaily (Oct. 5, 2010) — The oldest evidence of the dinosaur lineage -- fossilized tracks -- is described in Proceedings of the Royal Society B. Just one or two million years after the massive Permian-Triassic extinction, an animal smaller than a house cat walked across fine mud in what is now Poland.
http://www.sciencedaily.com/releases/2010/10/101006085311.htm