Abstract
According to evolutionary theory, the origin of tetrapods from a fish-like ancestor during the Devonian Period was one of the major events in the history of life on Earth. The 'drying pond' hypothesis was proposed to explain the selection pressures behind the transition. According to this hypothesis, the tetrapods evolved as fishes became progressively better adapted to terrestrial conditions during prolonged episodes of drought. Recently, however, the assumption that feet and legs evolved to facilitate life on the land has been called into question. The 'earliest' known tetrapods with feet and legs are now thought to have been aquatic animals; evolutionists therefore argue that feet and legs evolved in a shallow water environment and were only later co-opted for use on the land. This paper reviews the radical changes in thinking about the fish-tetrapod transition that have taken place in the evolutionary community. It also considers the chimeromorphic nature of Devonian tetrapods and fishes, and offers some critical comments on the evolutionary interpretation of their fossil record.