Robert Bakker suggested that plant-eating dinosaurs " invented" flowering plants. He concluded that while Late Jurassic browsers fed on foliage in the canopy and subcanopy layers, the later Cretaceous dinosaurs were predominately grazers that indiscriminately clipped flora to near-ground levels. And because angiosperms (flowering plants) grow and reproduce quickly, early angiosperms would have recovered from this clear- cutting faster than non-flowering gymnosperms, giving them a competitive advantage that eventually led to their dominance. Some argue, however, that most Cretaceous dinosaurs probably did not graze vegetation to the ground and that both angiosperm and gymnosperm seedlings would have survived. They also object to Bakker's comparison of widespread dinosaur herbivory to mammalian qrazing on grasslands, given the absence of evidence that such habitats occurred during the Cretaceous.