What are Tetrapods?
Tetrapods are vertebrate animals with four feet, legs or leglike appendages. In Greek, “tetrapod” means “four-legged”. Tetrapods include amphibians, reptiles, dinosaurs, birds, mammals, and a few ancient forms intermediate between fish and amphibians. A few tetrapods have evolved into legless forms, such as snakes. In scientific classification, Tetrapoda is a superclass within the subphylum Vertebrata. Whereas sharks, rays, skates, and fish are representatives of vertebrates in the seas, tetrapods are the representatives of vertebrates on land. Tetrapods evolved from the lobe-finned fishes (lungfish and coelacanths, also called Sarcopterygians), which possess lungs as well as gills. One of the first evolutionary steps towards tetrapods and away from fish was Panderichthys (dated to 380 million years ago), a fish with a large, tetrapod-like head, large strong fins on its underside, which probably lived in muddy shallows. Next was Tiktaalik (dated to 375 million years ago), sometimes cal
