 Long thought to be related to frigatebirds , cormorants , tropicbirds , gannets and boobies , pelicans instead are now known to be most closely related to the shoebill and hamerkop , and are placed in the order Pelecaniformes . <unk> , spoonbills and herons are more distant relatives , and have been classified in the same order . Fossil evidence of pelicans dates back to at least 30 million years to the remains of a beak very similar to that of modern species recovered from Oligocene strata in France . They are thought to have evolved in the Old World and spread into the Americas ; this is reflected in the relationships within the genus as the eight species divide into Old World and New World lineages . 
