the fossil record indicates that the ilex lineage was already widespread prior to the end of the cretaceous period based on the molecular clock the common ancestor of most of the extant species probably appeared during the eocene about  million years ago suggesting that older representatives of the genus belong to now extinct branches the laurel forest covered great areas of the earth during the paleogene when the genus was more prosperous this type of forest extended during the neogene more than  million years ago most of the last remaining temperate evergreen forests are believed to have disappeared about  years ago at the end of the pleistocene many of the then-existing species with the strictest ecological requirements became extinct because they could not cross the barriers imposed by the geography but others found refuge as a species relict in coastal enclaves archipelagos and coastal mountains sufficiently far from areas of extreme cold and aridity and protected by the oceanic influence