 Flying Cretaceous seabirds do not exceed wingspans of two meters; any sizes were taken by piscivorous pterosaurs.While "Hesperornis" is not thought to have left descendants, the earliest modern seabirds also occurred in the Cretaceous, with a species called "Tytthostonyx glauconiticus", which seems allied to the Procellariiformes and Pelecaniformes.In the Paleogene both pterosaurs and marine reptiles became extinct, allowing seabirds to expand ecologically.