>>16764352
>what is the operational definition of a leg
Operational definitions are less important than homology of structures in biology. Like how a fly has wings and legs, but they are completely different structures that arose independently. Meanwhile a bat’s wings have a different common name to a human’s hands but they both have pretty much all the same bones
>if it isnt connected to the hip and spine?
They are connected to a hip. Picrel is a closer look. We know a whale’s hips are hips even though modern whales don’t have legs because older ones still had tiny legs
>Why not call wings, arms then?
They are. We don’t call them arms in common usage but in biological terms they are a bird’s arms. They have fingers, shoulders, elbows, etc
>Why are seal flippers not legs?
Same as above. Seals still use their flippers as legs though