ABSTRACT
Phytophagy certainly started much before the appearance of flowering plants which date from the Cretaceous, or at least from the end of the Jurassic. The sexual parts of the plants were enclosed by leaflike organs, almost floral in appearance, with their ovules protected by scales. The tendency of the flowers of the fossil Bennetitales to increase in size is very typical. The most evolved of all pollinators, the bees, appeared last, along with the plants most adapted to that function, such as Compositae, Labiatae, Scrophulariaceae, Papilionaceae, and orchids. Leaf cutting and fungus growing ants in tropical America show the unique peculiarity of being both monophagous for the fungus they grow, and polyphagous, since they cut leaves of many kinds of trees. Pollination by animals also represents a form of coevolution which has lasted for more than 200 million years. Coevolutionary mechanisms, such as the production of a new alkaloid provide a means to fight back, in turn causing food selection.
