"The Saurus form one of the core species of the Lizardmen race, created by the Old Ones to be the warriors and guardians of their society. When the Temple-Cities are on the warpath, it is the Saurus who make up the hardened core of the fighting forces. This is of no surprise, for the Saurus were created solely for the purpose of warfare and nothing else. They are large and ferocious predator-warriors, so single-minded in their duties that they have no concept of thought, individuality or personality.

It is said that the Old Ones cultivated this race of reptilian warriors although whether they created them entirely, or raised them up from some primordial life form of the jungles, is not clear. What is assured, however, is their role and function. In the prehistory of the world, a time before the coming of Elves or Dwarfs, it was the Saurus who pacified the lands, fighting great battles and exterminating entire species in accordance with the Old Ones’ wishes."

- From the Warhammer Wiki