The Great Taurus are flying creatures of pure RAEG, manifesting itself in the form of a red, winged bull wreathed in flames and smoke. While one would think that this may be a Chaos Beast dedicated to Khorne, the reality is that it actually serves under Hashut. Yes, it is a bit confusing as both Hashut and Khorne share plenty of similarities, but the big difference is that Khorne has a hardon for skulls whilst Hashut has a hardon for bulls.
As flying bulls, these flying ribeyes reign supreme in the ashen wastes of the Dark Lands where they must battle Dragons, Goblins, Ogres Orcs, Trolls and Wyverns. Unless the Winds of Magic are blowing unusually strong, they seldom stray far from this region as is suffused by the Wind of Aqshy.
The Chaos Dwarves on the other hand, have plenty of legends floating around these flying bulls. One such legend dates back to their creation, in which the Great Tauri were once people of their race mutated in living bull-furnaces to serve the god Hashut and call them the Red Bulls of Hashut. There is also apparently a stable housing these guys beneath the great temple to the god in Zharr-Naggrund and powerful Chaos Dwarfs are able to ride them into battle.
Another legend is a couple of (unknown) gods originally sent the Great Taurus as a punishment for a terrible transgression that occurred in the heart of a once-fertile land. It is said that the inhabitants had begun to worship the Ruinous Powers, hurling those who would not give up their faith into an active caldera. The volcano then erupted laying waste to the land for hundreds of miles and from this inferno emerged the first Great Taurus to hunt down any survivors.
Whatever is the case, the Chaos Dwarves grew to respect these guys as a pretty good war mount, as the fire they breathe is hot enough to melt iron, and enemy weapons instantly soften and blunt as their wielders are about to deliver the blow. When they reach peak autistic anger, the flames would then burst out of their throat and eyes, which usually resolves with the creature smashing its way into a large regiment. Its hide is bright red, flickering with sparks and is thick enough to resist heavy blows.