Now that you've heard about the floral environment in which the Ceratopsians lived, you may ask, what did they eat?
Again this is a matter of debate. Ceratopsians consumed large quantities of greenery, that is known. As to exactly what that was, is debated because of their unusual method of chewing.
Rather than having grinding tooth planes, adapted for chewing quantities of resistant plant material for their prolonged lifespan, Ceratopsian dentitions were dominated by a scissor-like shearing action (Dodson, 1996).
The jaws slid past one another, and as a consequence of the angulation of the teeth, only a single tooth in each position was in wear (Dodson, 1996).
Both modern and fossil herbivores have exhibited some degree of shear in their dentition, however, in no other case has shear completely dominated over crushing and grinding (Dodson, 1996). Consequently, there are a couple of different theories as to the content of the Ceratopsian diet.
One interpretation is that the Ceratopsids consumed fleshy fruits that required very little effort to chew.
Another view is that they ate food that required extensive effort to chew, possibly a food that was inaccessible to other animals lacking in such teeth and jaws (Dodson, 1996). The suggestion was that they ate fibrous palm and cycad fronds.
Unfortunately, much like the gait debate, neither arguement is conclusive.