Quadrupeds.
There would have to be trillions of four-legged animals that exist on Earth.
Aves is a scientific name for birds.
Four-legged mammals are not a species (or any kind of taxon), so they do not have a scientific name.
The phobia of four legged animals can be referred to as zoophobia. This is the general term used for various phobia related to animals.
All four-legged animals are called Quadrupeds, 'quad' - four; 'ped' - foot.
Most four legged animals
A wren.
QUADROPOD
Bear Buffalo Bison Bird Answer. How many four legged birds are there?
cat
frog fox
skunksloth