Tiktaalik << tihk TAH lihk >> was a lobe-finned fish that was closely related to the first animals with legs. The first animals with legs are called early tetrapods. Some early tetrapods became the first vertebrates (animals with backbones) to live on land. Thus, all amphibians, birds, mammals, and reptiles descend from lobe-finned fish that were similar to Tiktaalik. Tiktaalik lived during the late part of the Devonian Period, about 375 million to 380 million years ago.
Tiktaalik had a body that was mostly covered in scales. It had a wide head with a flattened snout. Two rows of teeth—including several large fangs—lined the mouth. These teeth and other features indicate that Tiktaalik was a predator (hunting animal). The known fossils of Tiktaalik suggest it could reach about 9 feet (2.7 meters) long.
Tiktaalik is one of a series of fossils that show how certain lobe-finned fish developed features that would enable their descendants to live on land. These features were originally adaptations to life in shallow waters. Tiktaalik’s head and body were flattened, with eyes on the top of its skull. This arrangement is similar to that of crocodiles, which are likewise adapted to live in shallow water. Also, the bones of Tiktaalik’s front fins were arranged like limb bones. These fins were farther under the body than are the fins of most fish. Such limblike fins would have been useful for moving in shallow water. Also, Tiktaalik could probably use these fins to prop its upper body out of the water. That posture may have helped Tiktaalik to gulp air from the surface.
See also Coelacanth.
