Earliest tetrapod trackway

PZ Myers over at Phyrangula has a good summary of a recent paper about the discovery of what appears to be the oldest tetrapod trackway on Earth pushing the origin of amphibians from lobe-finned fish back some 20 million years to around 395 Ma - the early part of the Middle Devonian Period.  The transition of vertebrates from sea to land has become a bit more complicated than we thought.

Niedźwiedzki, G., Szrek, P., Narkiewicz, K., Narkiewicz, M., & Ahlberg, P. (2010).

Tetrapod trackways from the early Middle Devonian period of Poland.

Nature 463 (7277), 43-48