Tiktaalik is the fossil fish named in 2006 for showing features between fish and four-limbed vertebrates.
Fossils of Tiktaalik were discovered on Ellesmere Island in the Canadian Arctic and date from about 375 million years ago, during the Devonian Period. It had scales, fins, and fish-like characteristics, but also a mobile neck, robust ribs, and fin bones that resemble the early pattern of limb bones.
These traits do not make Tiktaalik a direct ancestor of every later land vertebrate. Instead, it is a close relative that helps document a stage in the evolutionary transition from finned vertebrates toward tetrapods. Its anatomy shows how structures used in water could be modified for support in shallow-water environments.
Tiktaalik is often called a “fishapod,” an informal nickname reflecting its mixture of traits. It lived before fully terrestrial tetrapods, including Acanthostega, appeared in the fossil record.