Plotopteridae they became extinct. That they became extinct at the same time as the giant penguins of the Southern Hemisphere, which also coincided with the radiation of the seals and dolphins, has led to speculation that the expansion of marine mammals was responsible for the extinction of the Plotopteridae, though this has not been formally tested. Plotopteridae Plotopteridae is the name of an extinct family of flightless seabirds from the order Suliformes. Related to the gannets and boobies, they exhibited remarkable convergent evolution with the penguins, particularly with the now extinct giant penguins. That they lived in the North Pacific, the
Marine mammal mammals emit loud and noxious underwater sounds. Two changes to the global atmosphere due to anthropogenic activity threaten marine mammals. The first is increases in ultraviolet radiation due to ozone depletion, and this mainly affects the Antarctic and other areas of the southern hemisphere. An increase in ultraviolet radiation has the capacity to decrease phytoplankton abundance, which forms the basis of the food chain in the ocean. The second effect of global climate change is global warming due to increased carbon dioxide levels in the atmosphere. Raised sea levels, sea temperature and changed currents are expected to affect marine mammals