Plant-eating dinosaurs did not eat grass, because there wasn’t any – so it is thought. During the Mesozoic Era, when the dinosaurs lived, conifers – cone-bearing trees and shrubs – dominated the landscape. They included redwoods, yews, pines, palms, cypress and the monkey puzzle tree. Flowering plants and grass evolved only later.
By the way, a plant does not look like its parents, but will always resemble its grandparents.