Grasses include some of the most useful plant life-forms. They became widespread towards the end of the Cretaceous period. Fossilized dinosaur dung (coprolites) have been found with phytoliths of grasses which are related to rice and bamboo. Grasses have adapted to conditions in lush rain forests, dry deserts, cold mountains and even intertidal habitats. They are at present the most widespread plant type. Grass is a valuable source of food and energy for wildlife as well as humans.