Wikipedia
Gavaevodata
Gavaevodata () is the Avestan language name of the primordial bovine of Zoroastrian cosmogony and cosmology, one of Ahura Mazda's six primordial material creations and the mythological progenitor of all beneficent animal life.
The primordial beast is killed in the creation myth, but from its marrow, organs and cithra the world is repopulated with animal life. The soul of the primordial bovine – geush urvan – returned to the world as the soul of livestock. Although geush urvan is an aspect of the primordial bovine in Zoroastrian tradition, and may also be that in the Younger Avesta, the relationship between the two is unclear in the oldest texts.