Nice shot of it! You don’t happen to have more pictures to share from the exhibitions?
Yep, the extra leg is a clever take on perspective. You’ll see it recreated faithfully by Adrian Perez Montejano in his Realmgate (a scenery piece that came into being after he got himself some wall reliefs; inspiration ping-ponging):
With colour, the Assyrian Lamassu statue would have looked something like this in the palace:
Also, see here for loads and loads of illustrations of ancient Mesopotamia.
The Mesopotamian lammasu statues are really interesting with their 5 legs. I did a research assignment on them a few years back. They were carved in a way so that if you looked at them from the front they would look guarding, and agressive. But if you walked by the would look like they were walking past you being passive, and kind. Truly a marvellous way to decorate a doorway.