Acanthostega

Acanthostega, from Ancient Greek ἄκανθα (ákantha), meaning "spine", and στέγη (stégē), meaning "roof", is an extinct genus of stem-tetrapod, among the first vertebrate animals to have recognizable limbs. It appeared in the late Devonian period (Famennian age) about 365 million years ago, and was anatomically intermediate between lobe-finned fishes and those that were able to come onto land.