Tetrapods are four-limbed vertebrates that evolved from lobe-finned fish during the Devonian (395 million years ago), invading the land and ultimately leading to today's the amphibians, reptiles, birds, and mammals.
These five fossils, summarized in the chart above, are important for understanding tetrapod evolution. Click on the links to go to the Wikipedia page, where you can find more details about each genus.
Featured image from H.P. Schultze & R. Cloutier via www.miguasha.ca.