A. Class-Aves
This class includes all birds. All birds have an outer covering of feathers, are endothermic (warm-blooded), have front limbs modified as wings, and lay eggs (Miller, 1993).
B. Order-Sphenisciformes
This order includes all living and extinct penguins.
C. Family-Spheniscidae
Spheniscidae includes all penguins, living and extinct, and is the only family classification in the order Sphenisciformes (del Hoyo, et al., 1992; Carroll, 1988).
D. Genus, species
1 . Most scientists recognize 17 species of penguins (del Hoyo, et al., 1992):
2. Some scientists recognize an 18th species: the white-flippered variety of fairy penguin, Eudyptula albosignata.
E. Fossil record
1 . Scientists recognize 32 species of extinct penguins (del Hoyo, et al., 1992).
2. Penguins probably evolved from flying birds more than 40 million years ago (Davis and Darby, 1990; Sparks and Soper, 1987). As the ancestors of penguins became adapted to an oceanic environment, structural changes for diving and swimming required the loss of flying adaptations (Simpson, 1976).
3. To date, the discovery of all penguin fossil fragments has been limited to the Southern Hemisphere. Records show that prehistoric penguins were found within the range of present-day penguins (Sparks and Soper, 1987).
a. The first penguin fossil fragments were found in New Zealand in the mid-1800s. One fossil penguin, Palaeeudyptes antarcticus, lived in the Eocene Period (38 to 42 million years ago) (Carroll, 1988). It was estimated to stand 1.2 to 1.5 m (4-5 ft.). This specimen is maintained in London's British Natural History Museum (Simpson, 1976).
b. Fossil records show that the largest extinct species lived in the Miocene Period (11 to 25 million years ago). Pachydyptes ponderosus probably stood 1.4 to 1.5 m (4.5-5 ft.) and may have weighed 90 to 135 kg (198-298 lb.), and Anthropomis nordenskjoldi probably stood 1.5 to 1.8 m (5-5.9 ft.) and weighed 90 to 135 kg (1 98-298 lb.) (Sparks and Soper, 1987). Measurements are estimates, since only a few bone fragments have been found.
4. Scientists believe that ancient penguins began disappearing about the same time that the number of prehistoric seals and small whales started increasing in the oceans. Some scientists hypothesize that seals, whales, and penguins may have competed for the same food source, and that the penguins may have become prey themselves. Both factors may have contributed to their extinction (Simpson, 1976).
5. The closest living relatives to penguins are in the order Procellariiformes (the albatrosses, shearwaters, and petrels) (Sparks and Soper, 1987), and the order Gaviiformes (loons and grebes) (del Hoyo, et al., 1992). DNA studies also suggest a relationship with the frigatebirds (order Pelecaniformes) (del Hoyo, et al., 1992).
F. Discovery of modern penguins
1 . The first European explorers to see penguins probably were part of the Portuguese expedition of Bartholomeu Dias de Novaes in 1487-88. They were the first to travel around what is now known as the Cape of Good Hope in southern Africa (del Hoyo, et al., 1992).
2. The first documentation of penguin sightings is credited to members of the Portuguese voyage of Vasco da Gama in 1497. They described penguins they saw along the southern coasts of Africa (del Hoyo, et al., 1992).
3. The discovery of South America's Magellanic penguin was chronicled during the journey of Spanish explorer Ferdinand Magellan in 1520 (del Hoyo, et al., 1992).
4. The origin of the word "penguin" has been a subject of debate. Researchers' and historians' theories range from references to the amount of fat (penguigo in Spanish and pinguis in Latin) penguins possess to the claim that the word was derived from two Welsh words meaning "white head" (Sparks and Soper, 1987). The most agreed-upon explanation is that "penguin" was used as a name for the now-extinct great auk, which the modern-day penguin resembles and for which it was mistaken (Simpson, 1976).
All 17 penguin species live in the Southern Hemisphere.
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