Browsers eat a variety of leafy vegetation, while grazers primarily eat grass.
The diet of ungulates is inferred in two ways. A recent reexamination of browsers and grazers was reported by Janis et al. A number of trends were evident. Mya, often interpreted as signaling a wholesale shift to grass-eaters at that time, but this data set shows no such sudden shift. The authors interpret this as evidence that the abundance and variety of plant life in the Early Miocene was much greater that is has been since.