What is the anatomical term for a two jointed leg?
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I think you are talking about plantigrade, digitigrade and unguligrade.

Please note that the number of joints in mammals does NOT vary, but only the relative length (and shape) of the different parts of the leg.




A Plantigrade walks on the sole of the foot. 'Sole' translates to 'planta' in Latin hence the name.


Examples: Human, squirrel, raccoons, ...
Below is a chimpanzee skeleton






A Digitigrade walks on the digits (the toes).


Examples: dog, cat, hyena, ...
Below is a cat skeleton






An Unguligrade walks on the nails. 'nail' translates to 'ungula' in Latin hence the name.


Examples: cow, reindeer, goat, ...
Below is a cow skeleton