> The only permanent bipeds of the animal kingdom alongside humans
Kangaroos?
replies(3):
Kangaroos?
What has 4 legs in the morning, 2 in the afternoon, and 3 in the evening?
The key here is how relaxed is the interpretation of "permanent".
Only the healthy adult form is taken into account generally, you wouldn't say that dragonflies are mainly swimming animals for example, even if they do spend most of their life underwater as larvae.
The point here is that kangaroos that are capable of bipedal motion will always choose quadrupedal motion at low speeds. While humans who can walk will always choose to walk when possible.