in teh evolution of vertebrates , identify the significance of being tetrapod?

Answer 1

The basic body plan of all land vertebrates is tetrapody--that is having four limbs. The tetrapod body plan evolved from the lobe-finned fishes which used front fins and back fins, which evolved into legs.

Any subsequent vertebrates, amphibians, reptiles, birds or mammals share this plan, or are derived from ancestors that had that plan (such as birds, whales, snakes, etc)