Alca Impennis. The great auk (Pinguinus impennis) is a species of flightless alcid that became extinct in the mid-19th century. It was the only modern species in the genus Pinguinus. It is not closely related to the birds now known as penguins, which were discovered later and so named by sailors because of their physical resemblance to the great auk. Illustrated page from "Extinct Birds" by Lionel Rothschild, published in 1907, and drawn by John Gerrard Keulemans (1842–1912).