name = Penguins
image_width = 250px
Gentoo Penguin, "Pygoscelis papua"
ordo = Sphenisciformes
ordo_authority = Sharpe, 1891| familia = Spheniscidae
familia_authority = Bonaparte, 1831
subdivision_ranks = Modern genera
For prehistoric genera, see Systematics
Penguins (order Sphenisciformes, family Spheniscidae) are a group of aquatic, flightless
birds living almost exclusively in the Southern Hemisphere.The number of penguin speciesis debated. Depending on which authority is followed, penguin biodiversityvaries between 17 and 20 living species, all in the subfamilySpheniscinae. Some sources consider the White-flippered Penguina separate " Eudyptula" species, while others treat it as a subspecies of the Little Penguin;Davis & Renner, (2003).] the actual situation seems to be more complicated.Banks "et al." (2002).] Similarly, it is still unclear whether the Royal Penguinis merely a color morph of the Macaroni penguin. Also eligible to be a separate species is the Northern population of Rockhopper penguins. Although all penguin species are native to the southern hemisphere, they are not, contrary to popular belief, found only in cold climates, such as Antarctica. In fact, only a few species of penguin actually live so far south. At least 10Verify source|date=May 2007 species live in the temperatezone: one; the Galápagos Penguin; lives as far north as the Galápagos Islands.
The largest living species is the
Emperor Penguin("Aptenodytes forsteri"): adults average about 1.1 m (3 ft 7 in) tall and weigh 35 kg (75 lb) or more. The smallest penguin species is the Little Blue Penguin (also known as the Fairy Penguin), which stands around 40 cm tall (16 in) and weighs 1 kg (2.2 lb). Among extant penguins larger penguins inhabit colder regions, while smaller penguins are generally found in temperate or even tropical climates ("see also" Bergmann's Rule). Some prehistoricspecies attained enormous sizes, becoming as tall or as heavy as an adult human (see below for more). These were not restricted to Antarctic regions; on the contrary, subantarcticregions harboured high diversity, and at least one giant penguin occurred in a region not quite 2,000 km south of the Equator35 mya , in a climate decidedly warmer than today.
Most penguins feed on
krill, fish, squid, and other forms of sealifecaught while swimming underwater. They spend half of their life on land and half in the oceans.
Penguins seem to have no special fear of humans and have approached groups of explorers without hesitation. This is probably on account of there being no land predators in
Antarcticaor the nearby offshore islands that preyon or attack penguins. Instead, penguins are at risk at sea from predators such as the leopard seal. Typically, penguins do not approach closer than about 3 meters (10 ft) at which point they become nervous. This is also the distance that Antarctic tourists are told to keep from penguins (tourists are not supposed to approach closer than 3 meters, but are not expected to withdraw if the penguins come closer).
Penguins are superbly adapted to an
aquaticlife. Their vestigial wings have become flippers, useless for flight in the air. In the water, however, penguins are astonishingly agile. Within the smooth plumagea layer of air is preserved, ensuring buoyancy. The air layer also helps insulate the birds in cold waters.On land, penguins use their tails and wings to maintain balance for their upright stance.
All penguins are countershaded for
camouflage– that is, they have a white underside and a dark (mostly black) upperside. A predator looking up from below (such as an orcaor a leopard seal) has difficulty distinguishing between a white penguin belly and the reflective water surface. The dark plumage on their backs camouflages them from above.
Diving penguins reach 6 to 12 km/h (3.7 to 7.5 mph), though there are reports of velocities of 27 km/h (17 mph) (which are more realistic in the case of startled flight). The small penguins do not usually dive deep; they catch their prey near the surface in dives that normally last only one or two minutes. Larger penguins can dive deep in case of need. Dives of the large Emperor Penguin have been recorded which reach a depth of 565 m (1,870 ft) and last up to 22 minutes.
Penguins either waddle on their feet or slide on their bellies across the snow, a movement called "tobogganing", which conserves energy while moving quickly. They also jump with both feet together if they want to move more quickly or cross steep or rocky terrain.
Penguins have an average sense of hearing for birds;Wever "et al." (1969).] this is used by parents and chicks to locate one another in crowded colonies.Jouventin "et al." (1999).] Their
eyes are adapted for underwater vision, and are their primary means of locating prey and avoiding predators; in air it has been suggested that they are nearsighted, although research has not supported this hypothesis.Sivak "et al." (1987).]
Penguins have a thick layer of insulating feathers which serve to keep them warm in water (heat loss in water is much greater than in air). The Emperor penguin (the largest penguin) has the largest body mass of all penguins, which further reduces relative surface area and heat loss. They also are able to control blood flow to their extremities, reducing the amount of blood which gets cold, but still keeping the extremities from freezing. In the extreme cold of the Antarctic winter, the females are at sea fishing for food leaving the males to brave the weather by themselves. They often huddle together to keep warm and rotate positions to make sure that each penguin gets a turn in the center of the heat pack.
They can drink salt water because their
supraorbital glandfilters excess salt from the bloodstream. [cite web |url=http://www.zoo.org/educate/fact_sheets/penguin/penguin.htm |title=Animal Fact Sheets |accessdate=2006-07-21] [cite web |url=http://www.stlzoo.org/animals/abouttheanimals/birds/penguins/humboldtpenguin.htm |title=Humboldt Penguin :: Saint Louis Zoo |accessdate=2006-07-21] [cite web |url=http://users.iafrica.com/b/bo/boulders/Vans%20book.htm |title=African Penguins and Penguins of the World |accessdate=2006-07-21] The salt is excreted in a concentrated fluid from the nasal passages.
Chinstrap Penguins in Antarctica] Penguins form monogamous pairs for a breeding season, though the rate the same pair recouples varies drastically. Most penguins lay two eggs in a clutch, though the two largest species, the Emperor and the King Penguins, lay only one.Williams "(The Penguins)" p. 23] With the exception of the Emperor Penguin in all penguins share the incubation duties. [Numata, M; Davis, L & Renner, M (2000) " [http://www.royalsociety.org.nz/includes/download.aspx?ID=94769 Prolonged foraging trips and egg desertion in little penguins ("Eudyptula minor")] ". "New Zealand Journal of Zoology" 27: 291-298] These incubation shifts can last days and even weeks as one member of the pair feeds at sea.
Penguin eggs are smaller than any other bird species when compared proportionally to the weight of the parent birds; at 52 grams, the Little Penguin egg is 4.7% of its mothers' weight, and the 450-gram Emperor Penguin egg is 2.3%. The relatively thick shell forms between 10 and 16% of the weight of a penguin egg, presumably to minimise risk of breakage in an adverse nesting environment. The yolk, too, is large, and comprises 22–31% of the egg. Some yolk often remains when a chick is born, and is thought to help sustain it if parents are delayed in returning with food.Williams "(The Penguins)" p. 24]
When mothers lose a
chick, they sometimes attempt to "steal" another mother's chick, usually unsuccessfully as other females in the vicinity assist the defending mother in keeping her chick. In some species, such as Emperor Penguins, young penguins assemble in large groups called crèches.
Perhaps one in 50,000 penguins (of most species) are born with brown rather than black plumage. These are called Isabelline penguins, possibly in reference to the legend that the archduchess
Isabella of Austriavowed not to change her undergarments until her husband united the northern and southern Low Countries by taking the city of Ostend – which took three years to accomplish. [ [http://www.notornis.org.nz/free_issues/Notornis_50-2003/Notornis_50_1_43.pdf] ] Isabellinism is different from albinism, though the faded color of the plumage calls albinism to mind. Isabelline penguins tend to live shorter lives than normal penguins, as they are not well-camouflaged against the deep, and are often passed over as mates.
ystematics and evolution
Emperor Penguins ("Aptenodytes forsteri"), the largest living species.] Updated after Marples (1962), Acosta Hospitaleche (2004), and Ksepka "et al." (2006).
Subfamily Spheniscinae – Modern penguins
Aptenodytes" – Great penguins
King Penguin, "Aptenodytes patagonicus"
Emperor Penguin, "Aptenodytes forsteri"
Pygoscelis" – Brush-tailed penguins
Adelie Penguin, "Pygoscelis adeliae"
Chinstrap Penguin, "Pygoscelis antarctica"
Gentoo Penguin, "Pygoscelis papua"
Eudyptula" – Little penguins
Little Blue Penguin, "Eudyptula minor"
Northern Little Penguin, "Eudyptula albosignata" (provisional)
Spheniscus" – Banded penguins
Magellanic Penguin, "Spheniscus magellanicus"
Humboldt Penguin, "Spheniscus humboldti"
Galapagos Penguin, "Spheniscus mendiculus"
African Penguin, "Spheniscus demersus"
Yellow-eyed Penguin, "Megadyptes antipodes"
Eudyptes" – Crested penguins
Fiordland Penguin, "Eudyptes pachyrynchus"
Snares Penguin, "Eudyptes robustus"
Erect-crested Penguin, "Eudyptes sclateri"
Southern Rockhopper Penguin, "Eudyptes chrysocome"
Northern Rockhopper Penguin, "Eudyptes moseleyi"
Royal Penguin, "Eudyptes schlegeli" (disputed)
Macaroni Penguin, "Eudyptes chrysolophus"
*Basal and unresolved taxa (all
Waimanu" – basal (Middle-Late Paleocene)
Perudyptes" (Middle Eocene of Atacama Desert, Peru) – basal?
**Spheniscidae gen. et sp. indet. CADIC P 21 (Leticia Middle Eocene of Punta Torcida, Argentina: Clarke "et al." 2003)
Delphinornis" (Middle/Late Eocene? – Early Oligocene of Seymour Island, Antarctica) – Palaeeudyptinae, basal, new subfamily 1?
Archaeospheniscus" (Middle/Late Eocene – Late Oligocene) – Palaeeudyptinae? New subfamily 2?
Marambiornis" (Late Eocene –? Early Oligocene of Seymour Island, Antarctica) – Palaeeudyptinae, basal, new subfamily 1?
Mesetaornis" (Late Eocene –? Early Oligocene of Seymour Island, Antarctica) – Palaeeudyptinae, basal, new subfamily 1?
Tonniornis" (Late Eocene –? Early Oligocene of Seymour Island, Antarctica)
Wimanornis" (Late Eocene –? Early Oligocene of Seymour Island, Antarctica)
Duntroonornis" (Late Oligocene of Otago, New Zealand) – possibly Spheniscinae
** "Korora" (Late Oligocene of S Canterbury, New Zealand)
Platydyptes" (Late Oligocene of New Zealand) – possibly not monophyletic; Palaeeudyptinae, Paraptenodytinae or new subfamily?
Spheniscusgen. et sp. indet (Late Oligocene/Early Miocene of Hakataramea, New Zealand)
Madrynornis" (Puerto Madryn Late Miocene of Argentina) – possibly Spheniscinae
Pseudaptenodytes" (Late Miocene/Early Pliocene)
** "Dege" (Early Pliocene of South Africa) – possibly Spheniscinae
Marplesornis" (Early Pliocene) – possibly Spheniscinae
Nucleornis" (Early Pliocene of Duinfontain, South Africa) – possibly Spheniscinae
Inguza" (Late Pliocene) – probably Spheniscinae; formerly "Spheniscus predemersus"
* Family Spheniscidae
Palaeeudyptinae– Giant penguins ( fossil)
Crossvallia" (Cross Valley Late Paleocene of Seymour Island, Antarctica) – tentatively assigned to this subfamily
Anthropornis" (Middle Eocene? – Early Oligocene of Seymour Island, Antarctica) – tentatively assigned to this subfamily
**** Nordenskjoeld's Giant Penguin, "
Icadyptes" (Late Eocene of Atacama Desert, Peru)
Palaeeudyptes" (Middle/Late Eocene – Late Oligocene) – polyphyletic; some belong in other subfamilies
Pachydyptes" (Late Eocene)
Anthropodyptes" (Middle Miocene) – tentatively assigned to this subfamily
Paraptenodytinae– Stout-footed penguins ( fossil)
Arthrodytes" (San Julian Late Eocene/Early Oligocene – Patagonia Early Miocene of Patagonia, Argentina)
Paraptenodytes" (Early – Late Miocene/Early Pliocene)
Palaeospheniscinae– Slender-footed penguins ( fossil)
Eretiscus" (Patagonia Early Miocene of Patagonia, Argentina)
Palaeospheniscus" (Early? – Late Miocene/Early Pliocene) – includes "Chubutodyptes"
Some recent sources [E.g. Clarke "et al." (2003), Ksepka "et al." (2006)] apply the phylogenetic taxon aut|Spheniscidae to what here is referred to as Spheniscinae. Furthermore, they restrict the phylogenetic taxon "Sphenisciformes" to flightless taxa, and establish the phylogenetic taxon aut|Pansphenisciformes as equivalent to the Linnean taxon Sphenisciformes,Clarke "et al." (2003).] i.e., including any flying basal "proto-penguins" to be discovered eventually. Given that neither the relationships of the penguin subfamilies to each other nor the placement of the penguins in the avian
phylogenyis presently resolved, this seems spuriousPOV-statement|date=July 2008 and in any case is confusing; the established Linnean system is thus followed here.
evolutionary history of penguins is well-researched and represents a showcase of evolutionary biogeography; though as penguin bones of any one species vary much in size and few good specimens are known, the alpha taxonomyof many prehistoric forms still leaves much to be desired. Some seminal articles about penguin prehistory have been published since 2005,Bertelli & Giannini, (2005).] Baker "et al." (2006).] Ksepka "et al." (2006).] Slack "et al." (2006).] the evolution of the living genera can be considered resolved by now.
The basal penguins lived around the time of the
Cretaceous–Tertiary extinction eventsomewhere in the general area of (southern) New Zealandand Byrd Land, Antarctica. Due to plate tectonics, these areas were at that time less than km to mi|1500 apart rather than the km to mi|4000 of today. The most recent common ancestorof penguins and their sister clade can be roughly dated to the Campanian– Maastrichtianboundary, around 70–68 mya. [The exact divergence dates according to Baker "et al." (2006) mentioned in this section are not as precisely resolved as it appears to be due to uncertainties of the molecular clockused.] What can be said as certainly as possible in the absence of direct (i.e., fossil) evidence is that by the end of the Cretaceous, the penguin lineage must have been evolutionarily well distinct, though much less so morphologically; it is fairly likely that they were not yet entirely flightless at that time, as flightless birds have generally low resilience to the breakdown of trophic webs which follows the initial phase of mass extinctions because of their below-average dispersal capabilities ("see also" Flightless Cormorant).
The basal fossils
The oldest known
fossilpenguin species is "Waimanu manneringi", which lived in the early Paleoceneepoch of New Zealand, or about 62 mya. While they were not as well-adapted to aquatic life as modern penguins, " Waimanu" were generally loon-like birds but already flightless, with short wings adapted for deep diving. They swam on the surface using mainly their feet, but the wings were – as opposed to most other diving birds, living and extinct – already adapting to underwater locomotion.
"Perudyptes" from northern Peru was dated to 42 mya. An unnamed fossil from
Argentinaproves that by the Bartonian(Middle Eocene), some 39–38 mya, ["Contra" Baker "et al." (2006).] primitive penguins had spread to South Americaand were in the process of expanding into Atlanticwaters.
During the Late Eocene and the Early
Oligocene(40–30 mya), some lineages of gigantic penguins existed. Nordenskjoeld's Giant Penguinwas the tallest, growing nearly 1.80 meters (6 ft) tall. The New Zealand Giant Penguinwas probably the heaviest, weighing 80 kg or more. Both were found on New Zealand, the former also in the Antarctic farther eastwards. Traditionally, most extinct species of penguins, giant or small, had been placed in the paraphyletic subfamilycalled Palaeeudyptinae. More recently, with new taxa being discovered and placed in the phylogenyif possible, it is becoming accepted that there were at least two major extinct lineages. One or two closely related ones occurred in Patagonia, and at least one other – which is or includes the paleeudyptines as recognized today – occurred on most Antarcticand subantarcticcoasts.
But size plasticity seems to have been great at this initial stage of penguin radiation: on
Seymour Island, Antarctica, for example, around 10 known species of penguins ranging in size from medium to huge apparently coexisted some 35 mya during the Priabonian(Late Eocene). [Jadwiszczak, (2006).] It is not even known whether the gigantic palaeeudyptines constitute a monophyleticlineage, or whether gigantism was evolved independently in a much restricted Palaeeudyptinae and the Anthropornithinae – whether they were considered valid, or whether there was a wide size range present in the Palaeeudyptinae as delimited as usually done these days (i.e., including " Anthropornis nordenskjoeldi"). The oldest well-described giant penguin, the 5-foot-tall " Icadyptes salasi", actually occurred as far north as northern Peruabout 36 mya.
In any case, the gigantic penguins had disappeared by the end of the
Paleogene, around 25 mya. Their decline and disappearance coincided with the spread of the Squalodontoidea and other primitive, fish-eating toothed whales, which certainly competed with them for food, and were ultimately more successful. A new lineage, the Paraptenodyteswhich includes smaller but decidedly stout-legged forms, had already arisen in southernmost South America by that time. The early Neogenesaw the emergence of yet another morphotype in the same area, the similarly-sized but more gracile Palaeospheniscinae, as well as the radiation which gave rise to the penguin biodiversityof our time.
Origin and systematics of modern penguins
Modern penguins consititute two undisputed
clades and another two more basal genera with more ambiguous relationships. The origin of the Spheniscinae lies probably in the latest Paleogene, and geographically it must have been much the same as the general area in which the order evolved: the oceans between the Australia-New Zealand region and the Antarctic. Presumedly diverging from other penguins around 40 mya, it seems that the Spheniscinae were for quite some time limited to their ancestral area, as the well-researched deposits of the Antarctic Peninsulaand Patagoniahave not yielded Paleogene fossils of the subfamily. Also, the earliest spheniscine lineages are those with the most southern distribution.
The genus "
Aptenodytes" appears to be the basalmost divergence among living penguins; they have bright yellow-orange neck, breast, and bill patches; incubate by placing their eggs on their feet, and when they hatch the chicks are almost naked. This genus has a distribution centered on the Antarctic coasts and barely extends to some subantarctic islands today.
Pygoscelis" contains species with a fairly simple black-and-white head pattern; their distribution is intermediate, centered on Antarctic coasts but extending somewhat northwards from there. In external morphology, these apparently still resemble the common ancestor of the Spheniscinae, as "Aptenodytes"' autapomorphies are in most cases fairly pronounced adaptations related to that genus' extreme habitatconditions. As the former genus, "Pygoscelis" seems to have diverged during the Bartonian, [In fact, it is fairly likely that during the Bartonian, there was a near-synchronous but allopatricsplit between the ancestors of "Aptenodytes", "Pygoscelis", and the common ancestor of all remaining genera [Baker "et al." (2006)] .] but the range expansion and radiation which led to the present-day diversity probably did not occur until much later; around the Burdigalianstage of the Early Miocene, roughly 20–15 mya.
The genera "
Spheniscus" and " Eudyptula" contain species with a mostly subantarctic distribution centered on South America; some, however, range quite far northwards. They all lack carotenoidcoloration, and the former genus has a conspicuous banded head pattern; they are unique among living penguins by nesting in burrows. This group probably radiated eastwards with the Antarctic Circumpolar Currentout of the ancestral range of modern penguins throughout the Chattian(Late Oligocene), starting approximately 28 mya. While the two genera separated during this time, the present-day diversity is the result of a Plioceneradiation, taking place some 4–2 mya.
The "Megadyptes"–"Eudyptes" clade occurs at similar
latitudes (though not as far north as the Galapagos Penguin), has its highest diversity in the New Zealand region, and represent a westward dispersal. They are characterized by hairy yellow ornamental head feathers; their bills are at least partly red. These two genera diverged apparently in the Middle Miocene ( Langhian, roughly 15–14 mya), but again, the living species of "Eudyptes" are the product of a later radiation, stretching from about the late Tortonian(Late Miocene, 8 mya) to the end of the Pliocene.
The geographical and temporal pattern or spheniscine evolution corresponds closely to two episodes of
global coolingdocumented in the paleoclimatic record. The emergence of the subantarctic lineage at the end of the Bartonian corresponds with the onset of the slow period of cooling that eventually led to the ice ages some 35 million years later. With habitat on the Antarctic coasts declining, by the Priabonian more hospitable conditions for most penguins existed in the subantarctic regions rather than in Antarctica itself. Notably, the cold Antarctic Circumpolar Current also started as a continuous circumpolar flow only around 30 mya, on the one hand forcing the Antarctic cooling, and on the other facilitating the eastward expansion of " Spheniscus" to South America and eventually beyond.
Later, an interspersed period of slight warming was ended by the
Middle Miocene Climate Transition, a sharp drop in global average temperature from 14–12 mya, and similar abrupt cooling events followed at 8 mya and 4 mya; by the end of the Tortonian, the Antarctic ice sheetwas already much like today in volume and extent. The emergence of most of today's subantarctic penguin species almost certainly was caused by this sequence of Neogene climate shifts.
Relationship to other bird orders
Penguin ancestry beyond "
Waimanu" remains unknown and not well-resolved by molecular or morphological analyses. The latter tend to be confounded by the strong adaptive autapomorphies of the Sphenisciformes; a sometimes perceived fairly close relationship between penguins and grebes is almost certainly an error based on both groups' strong diving adaptations, which are homoplasies. On the other hand, different DNA sequencedatasets do not agree in detail with each other either.
What seems clear is that penguins belong to a clade of Neoaves (living birds except
paleognaths and fowl) which comprises what is sometimes called "higher waterbirds" to distinguish them from the more ancient waterfowl. This group contains such birds as storks, rails, and the seabirds, with the possible exception of the Charadriiformes. [Fain & Houde, (2004).]
Inside this group, penguin relationships are far less clear. Depending on the analysis and dataset, a close relationship to
Ciconiiformesor to Procellariiformeshas been suggested. Some think the penguin-like plotopterids (usually considered relatives of anhingas and cormorants) may actually be a sister group of the penguins, and that penguins may have ultimately shared a common ancestor with the Pelecaniformesand consequently would have to be included in that order, or that the plotopterids were not as close to other pelecaniforms as generally assumed, which would necessitate splitting the traditional Pelecaniformes in three. [Mayr, (2005).]
Aukof the Northern Hemisphereis superficially similar to penguins: they are not related to the penguins at all, but considered by some to be a product of moderate convergent evolution. [ [http://evo.bio.psu.edu/hedgeslab/Publications/PDF-files/128.pdf Convergence and divergence in the evolution of aquatic birds] by Marcel Van Tuinen, Dave Brian Butvill, John A. W. Kirsch and S. Blair Hedges]
Penguins and humans
The word "Penguin" is thought by some to derive from the Welsh words "pen" (head) and "gwyn" (white), [http://dictionary.oed.com/cgi/entry/50174529?query_type=word&queryword=penguin&first=1&max_to_show=10&sort_type=alpha&result_place=1&search_id=e9qK-031OnY-14734&hilite=50174529 Oxford English Dictionary] . Accessed
2007-03-21.] applied to the Great Aukwhich had white spots in front of its eyes (although its head was black); or from an island off Newfoundland known as "Pengwyn", due to its having a large white rock. (In the latter case, the name may also have come from Breton.) This theory is supported by the fact that penguins look remarkably like Great Auks in general shape.
It is also possible that "penguin" comes from the
Latin"pinguis", “fat”. This is supported by the fact that the corresponding words in most other languages (e.g., French "pingouin", German "Pinguin") have "i" instead of "e" as the first vowel. However, a Welsh "i" is often sound-shifted to an "e" in the English language.Fact|date=March 2007
What may be a King Penguin but certainly is a member of the
Spheniscidaeappears on a 1599 map at the Strait of Magellanwith the caption "Pinguyn". The map's features are labeled in Latin, such as "Fretum Magellanicum" ("Strait of Magellan"). In addition, there is ample evidence that the Latin term "anser magellanicus" ("Goose of Magellan" or "Magellanic Goose") was the usual term for penguins in the scholarly literature of that time. If the English word was derived from Latin – e.g. "avis pinguis" ("fat bird") or "pinguinus" ("the fat one"Verify source|date=February 2008) – it must have originated considerably earlier than 1600.
In a final twist to the story, the term "Magellanic Goose" (today usually "
Magellan Goose") in our time has come to denote an actual anseriform, namely a " Chloephaga" sheldgoose.
The pronunciation of the word in English varies somewhat: as either "PEN-guin" or "PENG-guin".
Penguins in popular culture
Penguins are popular around the world, primarily for their unusually upright, waddling gait and (compared to other birds) lack of fear of humans. Their striking black-and-white plumage is often likened to a tuxedo suit. Mistakenly, some artists and writers have penguins based at the
North Pole. This is incorrect, as there are almost no wild penguins in the northern hemisphere, except the small group on the northernmost of the Galápagos.
Penguins have been the subject of many books and films such as "
Happy Feet" and "Surf's Up", both CGIfilms; " March of the Penguins", a documentary based on the migration process of Emperors; and a parody entitled " Farce of the Penguins". Penguins have also found their way into a number of cartoons and television dramas; perhaps the most notable of these is " Pingu", created by Silvio Mazzolain 1986 and covering more than 100 short episodes.
The tendency of penguins to form large groups feeds the stereotype that they all look exactly alike, a popular notion exploited by cartoonists such as
In the mid-2000s, penguins became one of the most publicized species of animals that form lasting homosexual couples. A children's book, "
And Tango Makes Three", was written about one such penguin family in the New York Zoo.
* [http://news.nationalgeographic.com/news/2007/06/070625-giant-penguins.html Two new fossil penguin species found in Peru]
* Acosta Hospitaleche, Carolina (2004): "Los pingüinos (Aves, Sphenisciformes) fósiles de Patagonia. Sistemática, biogeografía y evolución". Doctoral thesis, Department of Natural Sciences and Museum, Universidad Nacional de La Plata. La Plata, Argentina. [in Spanish] [http://www.sedici.unlp.edu.ar/search/request.php?id_document=ARG-UNLP-TPG-0000000084&request=request PDF fulltext]
* Baker, Allan J.; Pereira, Sergio Luiz; Haddrath, Oliver P. & Edge, Kerri-Anne (2006): Multiple gene evidence for expansion of extant penguins out of Antarctica due to global cooling. "Proc. R. Soc. B" 273: 11-17. doi|10.1098/rspb.2005.3260 [http://www.journals.royalsoc.ac.uk/content/pm36848701v24640/fulltext.pdf PDF fulltext]
* Banks, Jonathan C.; Mitchell, Anthony D.; Waas, Joseph R. & Paterson, Adrian M. (2002): An unexpected pattern of molecular divergence within the blue penguin ("Eudyptula minor") complex. "Notornis" 49(1): 29–38. [http://www.notornis.org.nz/free_issues/Notornis_49-2002/Notornis_49_1_29.pdf PDF fulltext]
* Bertelli, Sara & Giannini, Norberto P. (2005): A phylogeny of extant penguins (Aves: Sphenisciformes) combining morphology and mitochondrial sequences. "Cladistics" 21(3): 209–239. doi|10.1111/j.1096-0031.2005.00065.x (HTML abstract)
* Clarke, Julia A.; Olivero, Eduardo B. & Puerta, Pablo (2003): Description of the earliest fossil penguin from South America and first Paleogene vertebrate locality of Tierra Del Fuego, Argentina. "American Museum novitates" 3423: 1-18. [http://digitallibrary.amnh.org/dspace/bitstream/2246/2788/1/N3423.pdf PDF fulltext]
* Davis; Lloyd S. & Renner; M. (1995). "Penguins" . London: T & A D Poyser. ISBN 0-7136-6550-5
* Fain, Matthew G. & Houde, Peter (2004): Parallel radiations in the primary clades of birds. "Evolution" 58(11): 2558-2573. DOI|10.1554/04-235 [http://biology-web.nmsu.edu/houde/Parallel_radiations.pdf PDF fulltext]
* Jadwiszczak, Piotr (2006): Eocene penguins of Seymour Island, Antarctica: taxonomy. "Polish Polar Research" 27(1), 3–62. [http://www.polish.polar.pan.pl/ppr27/ppr27-003.pdf PDF fulltext]
* Jouventin, P; Aubin, T. & T Lengagne (1999) "Finding a parent in a king penguin colony: the acoustic system of individual recognition" "Animal Behaviour" 57: 1175–1183 [http://www.cb.u-psud.fr/animbehavkp.pdf]
* Ksepka, Daniel T., Bertelli, Sara & Giannini, Norberto P. (2006): The phylogeny of the living and fossil Sphenisciformes (penguins). "Cladistics" 22(5): 412–441. doi|10.1111/j.1096-0031.2006.00116.x (HTML abstract)
* Marples, B. J. (1962): Observations on the history of penguins. "In:" Leeper, G. W. (ed.), "The evolution of living organisms". Melbourne, Melbourne University Press: 408-416.
* Mayr, G. (2005): Tertiary plotopterids (Aves, Plotopteridae) and a novel hypothesis on the phylogenetic relationships of penguins (Spheniscidae). "Journal of Zoological Systematics and Evolutionary Research" 43(1): 61-71. doi|10.1111/j.1439-0469.2004.00291.x [http://www.senckenberg.de/files/content/forschung/abteilung/terrzool/ornithologie/plotopteridae.pdf PDF fulltext]
* Sivak, J.; Howland, H. & McGill-Harelstad, P. (1987) "Vision of the Humboldt Penguin (Spheniscus humboldti) in Air and Water " "Proceedings of the Royal Society of London. Series B, Biological Sciences". 229(1257): 467-472
* Slack, Kerryn E.; Jones, Craig M.; Ando, Tatsuro; Harrison G. L. "Abby"; Fordyce R. Ewan; Arnason, Ulfur & Penny, David (2006): Early Penguin Fossils, plus Mitochondrial Genomes, Calibrate Avian Evolution. "Molecular Biology and Evolution" 23(6): 1144-1155. DOI|10.1093/molbev/msj124 [http://mbe.oxfordjournals.org/cgi/reprint/23/6/1144 PDF fulltext] [http://mbe.oxfordjournals.org/cgi/content/full/msj124/DC1 Supplementary Material]
*Wever, E.; Herman, P.; Simmons, J. & Hertzler D (1969) "Hearing in the Blackfooted Penguin, Spheniscus demersus, as Represented by the Cochlear Potentials" "PNAS" 63(3): 676-680 [http://www.pnas.org/cgi/reprint/63/3/676]
* Williams; Tony D. (1995). "The Penguins - Spheniscidae" . Oxford: Oxford University Press. ISBN 0-19-854667-X
* [http://www.penguinworld.com Penguin World]
* [http://www.penguinpage.net penguinpage.net - Penguin research projects on the web]
* [http://www.70south.com/resources/antarctic-animals/antarctic-penguins Penguin information on 70South]
* [http://www.pinguins.info Information about penguins at pinguins.info]
* [http://www.pbs.org/wnet/nature/penguins/index.html PBS Nature: The World of Penguins]
* [http://www.itis.usda.gov Integrated Taxonomic Information System]
* [http://www.seaworld.org/infobooks/Penguins/home.html Seaworld Penguin Information]
* [http://ibc.hbw.com/ibc/phtml/familia.phtml?idFamilia=7 Penguin Videos] on the Internet Bird Collection
* [http://www.teara.govt.nz/EarthSeaAndSky/BirdsOfSeaAndShore/Penguins/en Penguins] in Te Ara the Encyclopedia of New Zealand
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