- Mammals: There are over 5,000 known mammal species, and a significant number of them are quadrupeds. Examples include dogs, cats, elephants, horses, bears, lions, tigers, wolves, gorillas, chimpanzees, and many others.
- Reptiles: Among reptiles, there are several four-legged species, including turtles, tortoises, lizards (such as the Komodo dragon and certain geckos), and crocodiles.
- Amphibians: Some amphibians, such as frogs and salamanders, have four legs.
- Birds: Although the majority of birds have wings and are considered bipedal (two-legged), there are a few exceptions. Ostriches, emus, and penguins are flightless birds that have four legs.
It's worth noting that this list is not exhaustive, and there may be additional four-legged animals among other animal groups. Therefore, it's difficult to provide a precise count of the total number of four-legged animals in the world.