Perhaps the most notable fossil in this story is an organism called Tikaalik rosea, an animal that had features intermediate between fish and tetrapods.For all the great comics regarding the transition from an aquatic life to (at least partially) terrestrial life- the Far Side panel of a pair of fish, one with a bat over his shoulder, looking at a baseball up on the beach comes to mind- this event is a profound one. I haven't thought much about it recently, but it's an environment I enjoy exploring in my imagination. I'm glad to have more information from the world of science to help flesh it out.
But Tiktaalik lived about 375 million years ago; and although there are slightly older transition fossils, the Zachelmie Quarry tetrapods break the neat and simple timeline.
"The discovery of undoubted trackways from the earliest period of the Eifelian - that is 379 million years ago - pushes back the divergence between fishes and the four-legged vertebrates by about 18 million years, if not probably more," commented Dr Philippe Janvier from the National Museum of Natural History, Paris, France.
"I suspect that now we can push the divergence back to the Emsian stage, maybe 400 million years ago. That's surprising, but this is what the fossil evidence tells us," the independent researcher told BBC News.
Followup: Here's the abstract of the paper from Nature. Via The Lancet, where the author, Martin Brazeau, says he'll post a detailed update soon.
Followup 2: The Guardian chimes in, with much the same info, but adding a nearly 10-minute long video that really helps clarify the details and importance of this find. Maybe a bit too docudramatic, but I enjoyed it. Field trip!
Followup 3: Nat Geo chimes in.