Early tetrapod evolution

Tetrapods include the only fully terrestrial vertebrates, but they also inc lude many amphibious, aquatic and flying groups, They occupy the highest le vels of the food chain on land and in aquatic environments. Tetrapod evolut ion has generated great interest but the earliest phases of their history a re poorly understood. Recent studies have questioned long-accepted hypothes es about the origin of the pentadactyl limb, the phylogeny of tetrapods and the environment in which the first tetrapods lived.