Seabird 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. These post-extinction seas were dominated by early Procellariidae, giant penguins and two extinct families, the Pelagornithidae and the Plotopteridae (a group of large seabirds that looked like the penguins). Modern genera began their wide radiation in the Miocene, although the genus "Puffinus" (which includes today's Manx shearwater and sooty shearwater) might date back to the Oligocene. The highest diversity of seabirds apparently existed during the Late Miocene and
Galápagos shearwater Galápagos shearwater The Galápagos shearwater ("Puffinus subalaris") is a small shearwater. Until recently it was considered to be a subspecies of Audubon's shearwater, but it is actually one of two members of a very ancient lineage of the small "Puffinus" species, the other being, as indicated by mtDNA cytochrome "b" sequence data, the Christmas shearwater. It is an endemic breeder of the Galápagos Islands, and is largely sedentary, although individuals are commonly seen as far as the Oaxacan coast of Mexico. The Galápagos shearwater has dark brown upperparts, undertail and underwing flight feathers, the rest of the underparts plumage being