Amphibians are the first true tetrapods, or vertebrates with four limbs, and animals with backbones are called vertebrates. Given these facts, amphibians are the first true what with four limbs among the following options:
- members of their own species
 - to move people
 - warm-blooded
 - Due to their feet
 - animals with backbones
 - remains of prehistoric life
 - Something to move
 - Generating heat


 

     animals with backbones    