From Wikipedia, the free encyclopedia.
A quadruped is an animal having exactly four limbs. This group includes mammals, some reptiles, amphibians. Althouth Birds have four limbs, they are usually not considered quadrupeds. The term quadruped doesn't apply to a taxonomic unit.
In contrast, the term tetrapoda applies to all animals with quadruped ancestors, i.e. all of the above-mentioned groups including the birds.
