Without plants, there would have been no dinosaurs (or any other land animals).
Plants are at the base of the food web (also called the food chain). Plants convert solar energy (sunlight) into chemical energy, which animals can eat. Plants are called “producers” or autotrophs because of this; they produce the fundamental food energy that all animals use.
Another amazing thing that plants do is change the composition of the air. Plants actually changed the chemical makeup of the Earth’s atmosphere by giving off oxygen and absorbing carbon dioxide. They also contribute to erosion and the creation of soil. Also, since plants are stationary, they determine where plant-eating animals live.
The development of plants was closely tied to the fate of the dinosaurs. Since most dinosaurs were plant-eaters, the nature and amount of available plants dictated whether a plant-eating dinosaur would thrive or die (and indirectly, would even influence the fate of meat-eating dinosaurs). As plants evolved through the Mesozoic Era, their distribution changed drastically, leading to the demise of some dinosaurs and the rise of new types of dinosaurs.