Sharpe , 1891 Family: Spheniscidae Bonaparte , 1831 Modern genera Aptenodytes Eudyptes Eudyptula Megadyptes Pygoscelis Spheniscus For prehistoric genera, see Systematics Penguins ( order Sphenisciformes, family Spheniscidae) are a group of aquatic , flightless birds living almost exclusively in the southern hemisphere , especially in Antarctica , where they are most