/jp/ - Otaku Culture

Six of the ten extant Sulidae species called boobies are in the genus Sula, while the three gannet species are usually placed in the genus Morus.[4] Abbott's booby was formerly included in Sula but is now placed in a monotypic genus Papasula, which represents an ancient lineage perhaps closer to Morus.
Some authorities consider that all ten species should be considered congeneric in Sula. However, they are readily distinguished by means of osteology. The distinct lineages of gannets and boobies are known to have existed in such form, since at least the Middle Miocene, c.15 mya.[5]
The fossil records of boobies are not as well documented as those of the gannets; possibly because the species of boobies were less numerous in the late Miocene to Pliocene, when gannets had their highest diversity or because of the more tropical distribution of boobies, many fossil species have simply not been found yet, as most localities are in continental North America or Europe.