Tiktaalik is one of the coolest fossils. This little guy was alive about 375 million years ago in the Devonian period. At that time the land was colonized with plants and arthropods, but vertebrates had yet to make the transition to life out of water. Tiktaalik was a predecessor of later vertebrates that did make that important transition to the land. Tiktaalik was a water animal and very fish-like but had limbs similar to land animals today. It probably used its limbs to move along the bottom of shallow lakes and streams and move over debris on the bottom. It may have been able to move out of the water for short periods of time, supported on its legs and primitive lungs. It still had fully developed gills, and was not quite an amphibian and still classified as a lobe-fined fish.