Menu Bull of Heaven 4020.05

K) The bull of heaven, so called, represents the soul of the world. It's name is geush urvan. The soul of the bull, killed by the enemy of life, Ahriman.

MZ) I am not sure about that really. The Bull of Heaven is a middle-eastern/Babylonian concept whereas the soul of the world/ox is pure Iranian as you know. The Bull of Heaven comes from the star constellation of Taurus, whereas the Gathic 'ox/cow/bull' comes from the real life cattle that the Iranians herded.
It makes sense for Mithras to kill the bull of heaven, but none at all for him to kill the soul of the world (or the cattle that the early Iranians depended on for their living).
Although it is tempting to try and make the connection, I think it best just to accept that there isn't one.