Tiktaalik: When fish met pushups

Tiktaalik is a monospecific genus of extinct lobe-finned fish. It is monospecific because Tiktaalik roseae is the only species classified under the genus. It lived during the Late Devonian Period about 375 million years ago, and although it generally had the characteristics of a lobe-finned fish, it also had traits similar to tetrapods. Not only did Tiktaalik have gills, scales and fins, like a fish, it also had rib bones, lungs and a mobile neck. It also had intermediate features, such as radiating, fish-like fins coupled with a functional wrist joint, and a half-fish, half-tetrapod ear region. Because of its amalgamation of features, Tiktaalik is referred to as a "transitional fossil": while not an ancestor to any living animal, it is evidence of the intermediate forms that bridged the evolutionary gap between fish with fins and animals with arms and legs.