Revision as of 18:59, 13 March 2007 view sourceSeb-moore (talk | contribs)3 editsNo edit summary← Previous edit | Revision as of 18:59, 13 March 2007 view source AntiVandalBot (talk | contribs)258,750 editsm BOT - rv Seb-moore (talk) to last version by Stephenchou0722Next edit → | ||
Line 2: | Line 2: | ||
{{Taxobox | {{Taxobox | ||
| color = pink | | color = pink | ||
| name = Penguins |
| name = Penguins | ||
| fossil_range = ]-Recent | | fossil_range = ]-Recent | ||
| image = Manchot 01.jpg | | image = Manchot 01.jpg | ||
| image_width = 250px | | image_width = 250px | ||
| image_caption = ], '' |
| image_caption = ], ''Pygoscelis antarctica'' | ||
| regnum = ]ia | | regnum = ]ia | ||
| phylum = ] | | phylum = ] | ||
| classis = ] | | classis = ] | ||
| ordo = ''' |
| ordo = '''Sphenisciformes''' | ||
| ordo_authority = ], ] | | ordo_authority = ], ] | ||
| familia = |
| familia = '''Spheniscidae''' | ||
| familia_authority = |
| familia_authority = ], ] | ||
| subdivision_ranks = Modern ] | |||
| subdivision = | | subdivision = | ||
* '']'' | |||
* bonnera | |||
* '']'' | |||
bonnery | |||
* '']'' | |||
bonneray]] | |||
* '']'' | |||
Bonner is a penguin and he mates with them. | |||
* '']'' | |||
Bonner is a penguin and he mates with them. | |||
* '']'' | |||
Bonner is a penguin and he mates with them. | |||
* For prehistoric genera, see ] | |||
Bonner is a penguin and he mates with them. | |||
}} | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
'''Penguins''' (] '''Sphenisciformes''', ] '''Spheniscidae''') are a group of ], ]s living almost exclusively in the ]. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
The number of penguin ] has been and still is a matter of debate. Depending on which authority is followed, ] varies between 17 and 20 living species, all in the ] '''Spheniscinae'''. Some sources consider the ] a separate '']'' species, while others treat it as a subspecies of the ] (e.g. Williams, 1995; Davis & Renner, 2003); the actual situation seems to be more complicated (Banks ''et al.'' 2002). Similarly, it is still unclear whether the ] is merely a color morph of the ]. Also possibly eligible to be treated as a separate species is the Northern population of ] (Davis & Renner, 2003). Although all penguin species are native to the southern hemisphere, they are not, contrary to popular belief, found only in cold climates, such as ]. In fact, only a few species of penguin actually live so far south. Three{{check}} species live in the ] zone; one lives as far north as the ] (the ]). | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
The largest living species is the ] (''Aptenodytes forsteri''): adults average about 1.1 m (3 ft 7 in) tall and ] 35 kg (75 lb) or more. The smallest penguin species is the ] (also known as the Fairy Penguin or the Blue Penguin), which stands around 40 cm tall (16 in) and weighs 1 kg (2.2 lb). Generally larger penguins retain heat better, and thus inhabit colder regions, while smaller penguins are found in temperate or even tropical climates (''see also'' ]). Some ] species attained enormous sizes, becoming as high or as heavy as an adult human; see below for more. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Most penguins feed on ], ], ], and other forms of ] caught while swimming underwater. They spend half of their life on land and half in the oceans. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Penguins seem to have no fear of humans and have approached groups of explorers without hesitation. This is probably on account of there being no land predators in ] or the nearby offshore islands that ] on or attack penguins. Instead, penguins are at risk at sea from predators such as the ]. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
A new study by released in January of 2007, found that 80% of penguins were left handed. The findings concluded that penguins use their dominant flipper for everything from building nests to moving other penguins out of the way. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
== Anatomy == | |||
Bonner is a penguin and he mates with them. | |||
Penguins are superbly adapted to an aquatic life. Their ]s have become flippers, useless for flight in the air. In the water, however, penguins are astonishingly agile. Within the smooth ] a layer of air is preserved, ensuring buoyancy. The air layer also helps insulate the birds in cold waters. | |||
Bonner is a penguin and he mates with them. | |||
On land, penguins use their ]s and wings to maintain balance for their upright stance. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
All penguins are ] - that is, they have a white underside and a dark (mostly black) upperside. This is for ]. A predator looking up from below (such as an ] or a ]) has difficulty distinguishing between a white penguin belly and the reflective water surface. The dark plumage on their backs camouflages them from above. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
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 ] have been recorded which reach a depth of 565 m (1870 ft) and last up to 22 minutes. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Penguins either waddle on their feet or slide on their bellies across the snow, a movement called "tobogganing", which allows them to conserve energy and move relatively fast at the same time. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Penguins have an excellent sense of ]. Their ]s are adapted for underwater vision, and are their primary means of locating prey and avoiding predators; in air, conversely, they are ]. Their sense of smell has not been researched so far. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
They are able to drink salt water safely because their ] filters excess salt from the bloodstream. <ref>{{cite web | url=http://www.zoo.org/educate/fact_sheets/penguin/penguin.htm | title=Animal Fact Sheets | accessdate=2006-07-21}}</ref><ref>{{cite web | url=http://www.stlzoo.org/animals/abouttheanimals/birds/penguins/humboldtpenguin.htm | title=Humboldt Penguin :: Saint Louis Zoo | accessdate=2006-07-21}}</ref><ref>{{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}}</ref> The salt is excreted in a concentrated fluid from the nasal passages. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
== Mating habits == | |||
Bonner is a penguin and he mates with them. | |||
Some penguins mate for life, others for just one season. They generally raise a small brood, and the parents cooperate in caring for the clutch and for the young. During the cold season on the other hand the mates separate for several months to protect the egg. Usually, the male stays with the egg and keeps it warm, and the female goes out to sea and finds food so that when it comes home, the baby will have food to eat. Once the female comes back, they switch roles. When mothers lose a ], 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. As the young grow, they assemble in large groups called ]s in some species, such as ]s. There are some cases where penguins of the same sex do pair. <ref>{{cite web | url=http://www.jrn.columbia.edu/studentwork/cns/2002-06-10/591.asp | title=Columbia News Service: June 10, 2002: They're in love. They're gay. They're penguins... And they're not alone. | accessdate=2006-07-21}}</ref><ref>{{cite web | url=http://www.365gay.com/newscon05/02/021105penguins.htm | title=365gay.com: Gay Penguins Resist 'Aversion Therapy' | accessdate=2006-07-21}}</ref> | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
==Systematics and evolution== | |||
Bonner is a penguin and he mates with them. | |||
===Systematics=== | |||
Bonner is a penguin and he mates with them. | |||
Updated after Marples (1962), Acosta Hospitaleche (2004), and Ksepka ''et al.'' (2006). See the ] for images of most living species. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
'''ORDER SPHENISCIFORMES''' | |||
Bonner is a penguin and he mates with them. | |||
*'''] and unresolved taxa''' | |||
Bonner is a penguin and he mates with them. | |||
** '']'' - basal (Middle-Late Eocene) | |||
Bonner is a penguin and he mates with them. | |||
**Sphenisciformes gen. et sp. indet. CADIC P 21 (Leticia Middle Eocene of Punta Torcida, Argentina: Clarke ''et al.'' 2003) | |||
Bonner is a penguin and he mates with them. | |||
* '''Family Spheniscidae''' | |||
Bonner is a penguin and he mates with them. | |||
** '''Subfamily ]''' - Giant penguins (]) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Cross Valley Late Paleocene of Seymour Island, Antarctica) - tentatively assigned to this subfamily | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Middle Eocene ?- Early Oligocene of Seymour Island, Antarctica)<!-- Cladistics22:412 --> | |||
Bonner is a penguin and he mates with them. | |||
**** Nordenskjoeld's Giant Penguin, '']'' | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Middle/Late Eocene - Late Oligocene) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Middle/Late Eocene ?- Early Oligocene of Seymour Island, Antarctica) - tentatively assigned to this subfamily<!-- Cladistics22:412 --> | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Late Eocene -? Early Oligocene of Seymour Island, Antarctica) - tentatively assigned to this subfamily<!-- Cladistics22:412 --> | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Late Eocene -? Early Oligocene of Seymour Island, Antarctica) - tentatively assigned to this subfamily<!-- Cladistics22:412 --> | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Middle/Late Eocene - Late Oligocene) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Late Eocene) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Late Oligocene of New Zealand) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Middle Miocene) - tentatively assigned to this subfamily | |||
Bonner is a penguin and he mates with them. | |||
** '''Subfamily ]''' - Patagonian stout-legged penguins (])<!-- American Museum novitates 2488: 1 --> | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (San Julian Late Eocene/Early Oligocene - Patagonia Early Miocene of Patagonia, Argentina)<!-- American Museum novitates 2488:1; Cladistics22:412 where lapsus "-dyptes" --> | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Early - Late Miocene/Early Pliocene) | |||
Bonner is a penguin and he mates with them. | |||
** '''Subfamily ]''' - Patagonian slender-legged penguins (]) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Patagonia Early Miocene of Patagonia, Argentina)<!-- Cladistics22:412 --> | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Early? - Late Miocene/Early Pliocene) - includes ''Chubutodyptes'' | |||
Bonner is a penguin and he mates with them. | |||
** '''Subfamily Spheniscinae''' - Modern penguins | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' - Great penguins (2 species) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' - Brush-tailed penguins (3 species) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' - Little penguins (2 species) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' - Banded penguins (4 species) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' - Yellow-eyed Penguin | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' - Crested penguins (5-7 living species, possibly another one recently ]) | |||
Bonner is a penguin and he mates with them. | |||
** '''Not assigned to a subfamily''' (all ]) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Late Eocene -? Early Oligocene of Seymour Island, Antarctica) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Late Eocene -? Early Oligocene of Seymour Island, Antarctica) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Late Oligocene of Otago, New Zealand) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Late Oligocene of S Canterbury, New Zealand) | |||
Bonner is a penguin and he mates with them. | |||
*** Spheniscidae gen. et sp. indet (Late Oligocene/Early Miocene of Hakataramea, New Zealand) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Late Miocene/Early Pliocene) | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' (Pliocene)<!-- Cladistics22:412 --> | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' - possibly Spheniscinae<!-- Cladistics22:412 --> | |||
Bonner is a penguin and he mates with them. | |||
<!-- *** '']'' - possibly Spheniscinae --> | |||
Bonner is a penguin and he mates with them. | |||
*** '']'' - possibly Spheniscinae<!-- Cladistics22:412 - lapsus "Nucleaornis" --> | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
'''Taxonomy''': Clarke ''et al.'' (2003) and Ksepka ''et al.'' (2006) apply the ] <span style="font-variant:small-caps">Spheniscidae</span> to what here is referred to as Spheniscinae. Furthermore, they restrict the phylogenetic taxon <span style="font-variant:small-caps">Sphenisciformes</span> to flightless taxa, and establish (Clarke ''et al.'' 2003) the phylogenetic taxon <span style="font-variant:small-caps">Pansphenisciformes</span> as equivalent to the ] Sphenisciformes, 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 ] is presently resolved, this seems spurious and in any case is confusing; the established Linnean system is thus followed here. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
===Evolution=== | |||
Bonner is a penguin and he mates with them. | |||
The ]ary history of penguins is by now fairly well researched and represents a showcase of evolutionary ]; though as penguin bones of any one species vary much in size and few good specimens are known, the ] of many prehistoric forms still leaves much to be desired. A number of seminal articles dealing with penguin prehistory has been published since ] (Bertelli & Giannini 2005, Baker ''et al.'' 2006, Ksepka ''et al.'' 2006, Slack ''et al.'' 2006), and at least the evolution of the living genera can be considered resolved by now. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
According to the comprehensive review of the available evidence by Ksepka ''et al.'' (2006), the ] penguins lived around the time of the ] somewhere in the general area of (southern) ] and ], Antarctica. Due to ], these areas were at that time less than 1500 ]s apart rather than the 4000 km of today. The ] of penguins and their ] can be roughly dated to the ]-] boundary, around 70-68 mya (Baker ''et al.'' 2006, Slack ''et al.'' 2006)<ref> | |||
Bonner is a penguin and he mates with them. | |||
The seemingly 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 uncertainities of the ] used.</ref> | |||
Bonner is a penguin and he mates with them. | |||
What can be said as certainly as possible in the absence of direct (i.e., fossil) evidence is that by the end of the ], the penguin lineage must have been evolutionarily well distinct, though much less so ]; it is fairly likely that they were not yet flightless at that time, as flightless birds have generally low resilience to the breakdown of ]s which follows the initial phase of mass extinctions (''see also'' ]). | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
'''The oldest fossils'''<br/> | |||
Bonner is a penguin and he mates with them. | |||
The oldest known ] penguin species is ''Waimanu manneringi'', which lived in the early ] epoch of ], or about 62 ] (Slack ''et al.'' 2006). While they were not as well adapted to aquatic life as modern penguins, '']'' were generally ]-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. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
An unnamed fossil from ] proves that by the ] (Middle ]), some 39-38 mya<ref> | |||
Bonner is a penguin and he mates with them. | |||
''Contra'' Baker ''et al.'' (2006).</ref>, | |||
Bonner is a penguin and he mates with them. | |||
primitive penguins had spread to ] and were in the process of expanding into ] waters (Clarke ''et al''. 2003). | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
'''"Palaeeudyptines"'''<br/> | |||
Bonner is a penguin and he mates with them. | |||
During the Late Eocene and the Early ] (40-30 mya), some lineages of gigantic penguins existed. ] was the tallest, growing nearly 1.80 meters (6 feet) tall. The ] was probably the heaviest, weighing 80 kg or more. Both were found on ], the former also in the Antarctic farther eastwards. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Traditionally, most extinct species of penguins, giant or small, had been placed in the ] ] called ]. More recently, with new taxa being discovered and placed in the ] if possible, it is becoming accepted that there were at least 2 major extinct lineages. One or two closely related ones occurred in ], and at least one other - which is or includes the paleeeudyptines as recognized today - occurred on most ] and ] coasts. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
But size plasticity seems to have been great at this initial stage of penguin ]: on ], Antarctica, for example, around ten known species of penguins ranging from medium to huge size apparently coexisted some 35 mya during the ] (Late Eocene) (Jadwiszczak 2006). It is not even known whether the gigantic palaeeudyptines constitute a ] lineage, or whether gigantism was evolved independently in a much restricted Palaeeudyptinae and the Anthropornithinae - were they considered valid -, or whether there was a wide size range present in the Palaeeudyptinae as delimited as usually done these days (i.e., including '']'') (Ksepka ''et al.'' 2006). | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
In any case, the gigantic penguins had disappeared by the end of the ], around 25 mya. Interestingly, their decline and disappearance coincides with the spread of the ] and other primitive, fish-eating ]s, which certainly competed with them for food, and were ultimately more successful (Baker ''et al.'' 2006). A new lineage, the ] which includes smaller but decidedly stout-legged forms, had already arisen in southernmost South America by that time. The early ] saw the emergence of yet another morphotype in the same area, the similarly-sized but more gracile ], as well as the radiation which gave rise to the penguin ] of our time. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
'''Origin and systematics of modern penguins'''<br/> | |||
Bonner is a penguin and he mates with them. | |||
Modern penguins consititute two undisputed ]s and another two more basal genera with more ambiguous relationships (Bertelli & Giannini 2005). 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 (Baker ''et al.'' 2006). Presumedly diverging from other penguins around 40 mya (Baker ''et al.'' 2006), it seems that the Spheniscinae were for quite some time limited to their ancestral area, as the well-researched deposits of the ] and ] have not yielded Paleogene fossils of the subfamily. Also, the earliest spheniscine lineages are those with the most southern distribution. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
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, they are almost naked. This genus has a distribution centered on the Antarctic coasts and barely extends to some subantarctic islands today. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
''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 ], these apparently still resemble the common ancestor of the Spheniscinae, as ''Aptenodytes''' ]ies are in most cases fairly pronounced ]s related to that genus' extreme ] conditions. As the former genus, it seems to have diverged during the Bartonian<ref> | |||
Bonner is a penguin and he mates with them. | |||
In fact, it is fairly likely that during the Bartonian, there was a near-synchronous split between the ancestors of ''Aptenodytes'', ''Pygoscelis'', and the common ancestor of all remaining genera (Baker ''et al.'' 2006).</ref>, | |||
Bonner is a penguin and he mates with them. | |||
but the range expansion and radiation which lead to the present-day diversity probably did not occur until much later, around the ] stage of the Early ], roughly 20-15 mya (Baker ''et al.'' 2006). | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
The ] ''Spheniscus'' and ''Eudyptula'' contain species with a mostly subantarctic distribution centered on ]; some, however, range quite far northwards. They all lack ] coloration, and the former genus has a conspicuous banded head pattern; they are unique among living penguins in nesting in burrows. This group probably radiated eastwards with the ] out of the ancestral range of modern penguins throughout the ] (Late Oligocene), starting approximately 28 mya (Baker ''et al.'' 2006). While the two genera separated during this time, the present-day diversity is the result of a ] radiation, taking place some 4-2 mya (Baker ''et al.'' 2006). | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
The ''Megadyptes'' - ''Eudyptes'' clade occurs at similar ]s (though not as far north as the ]), 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 (], roughly 15-14 mya), but again, the living species of ''Eudyptes'' are the product of a later radiation, stretching from about the late ] (Late Miocene, 8 mya) to the end of the Pliocene (Baker ''et al.'' 2006). | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
It is most interesting to note that the geographical and temporal pattern or spheniscine evolution corresponds closely to two episodes of ] documented in the ] (Baker ''et al.'' 2006). 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 ]s 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 enabling the eastward expansion of ''Spheniscus'' to South America and eventually beyond (Baker ''et al.'' 2006). | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Later, an interspersed period of slight warming was ended by the ], a sharp drop in global average temperature from 14 to 12 mya, and similar abrupt cooling events followed at 8 mya and 4 mya; by the end of the Tortonian, the ] was 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. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
'''Relationship to other bird orders'''<br/> | |||
Bonner is a penguin and he mates with them. | |||
Penguin ancestry beyond ''Waimanu'' remains unknown and not well resolved by molecular or morphological analyses. The latter tend to be confounded by the strong adative autapomorphies of the Sphenisciformes; a sometimes perceived fairly close relationship between penguins and ]s is almost certainly an error based on both groups' strong diving adaptations, which are ]. On the other hand, different ] datasets do not agree in detail with each other either. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
What seems clear is that penguins belong to a clade of ] (living birds except ]s and ]) which comprises of what is sometimes called "higher waterbirds" to distinguish them from the more ancient ]. This group contains such birds as ]s, ]s, and the ]s, with the possible exception of the ] (Fain & Houde 2004). | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Inside this group, penguin relationships are far less clear. Depending on the analysis and dataset, a close relationship to ] (e.g. Slack ''et al.'' 2006) or to ] (Baker ''et al.'' 2006) has been suggested. Some (e.g. Mayr 2005) think the penguin-like ] (usually considered relatives of ]s and ]s) may actually be a sister group of the penguins, and that penguins may have ultimately shared a common ancestor with the ] and 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. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
== Name == | |||
Bonner is a penguin and he mates with them. | |||
''Penguin'' is thought by some to derive from the ] words ''pen'' (head) and ''gwyn'' (white), applied to the ], which had a conspicuous white patch between the bill and the eye (although its head was black), or from an island off Newfoundland known as "White Head" due to a large white rock. This may be, however, a false etymology created by Dr. John Dee in his book on Prince ] of Wales, supposedly one of the discoverers of America. By this Dee hoped to cement ]'s claim, as a ], to the New World. Penguins live nowhere near Newfoundland, nor do they generally have white heads, but they do look remarkably like Great Auks in general shape. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
According to another theory, the original name was ''pen-wing'', with reference to the rudimentary wings of both Great Auks and penguins. A third theory is that ''penguin'' comes from the ] ''pinguis'' (fat). This has added credibility because the two other ], ] 'pinguïn' and ], 'Pinguin', as well as the ] 'пингвин' ('pingvin') all have the 'i' vowel as well. While it has been replaced by an 'e' in the ] spelling, the "i" can still be heard. By simply looking at the word's pronunciation and comparing that to the Dutch, German, and Russian words, one could assume a common Latin root - after the ] (500-200 BC) that makes a ] 'p' into a 'f'. However, a Welsh 'i' is often sound-shifted to an 'e' in the English language, so a Welsh origin cannot be dismissed. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
== Penguins in popular culture == | |||
Bonner is a penguin and he mates with them. | |||
] the ] mascot]] | |||
Bonner is a penguin and he mates with them. | |||
{{main|Penguins in popular culture}} | |||
Bonner is a penguin and he mates with them. | |||
Penguins are popular around the world, primarily for their unusually upright, waddling pace and (compared to other birds) lack of fear of humans. Their striking black and white plumage is often likened to a ] suit and generates humorous remarks about the bird being "well dressed". Perhaps in reaction to this cutesy stereotype, fictional penguins are occasionally presented as grouchy or even sinister. Penguins have also been the subject of many books and documentary films. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
==Gallery of living species== | |||
Bonner is a penguin and he mates with them. | |||
<gallery> | |||
Bonner is a penguin and he mates with them. | |||
Image:Emperor penguins.jpg|]s<br/>''Aptenodytes forsteri'' | |||
Bonner is a penguin and he mates with them. | |||
Image:Koenigspinguine.jpg|]s<br/>''Aptenodytes patagonicus'' | |||
Bonner is a penguin and he mates with them. | |||
Image:penguin2.jpg|]s<br/>''Pygoscelis adeliae'' | |||
Bonner is a penguin and he mates with them. | |||
Image:penguinu.jpg|] (''Pygoscelis antarctica'') hunting for ] | |||
Bonner is a penguin and he mates with them. | |||
image:Pygoscelis_papua.jpg|]<br/>''Pygoscelis papua'' | |||
Bonner is a penguin and he mates with them. | |||
Image:Eudyptes chrysocome.jpg|]<br/>''Eudyptes chrysocome'' | |||
Bonner is a penguin and he mates with them. | |||
Image:Fiordland penguin (Mattern).jpg|]<br/>''Eudyptes pachyrhynchus'' | |||
Bonner is a penguin and he mates with them. | |||
Image:SnaresPenguin (Mattern).jpg|]<br/>''Eudyptes robustus'' | |||
Bonner is a penguin and he mates with them. | |||
Image:MacaroniPenguinJM.jpg|]<br/>''Eudyptes chrysolophus'' | |||
Bonner is a penguin and he mates with them. | |||
Image:MegadyptesAntipodes.jpg|]<br/>''Megadyptes antipodes'' | |||
Bonner is a penguin and he mates with them. | |||
Image:Little Penguin.jpg|] or Fairy Penguin<br/>''Eudyptula minor'' | |||
Bonner is a penguin and he mates with them. | |||
Image:penguin.jackass.arp.500pix.jpg|] or Jackass Penguin<br/>''Spheniscus demersus'' | |||
Bonner is a penguin and he mates with them. | |||
Image:Spheniscus mendiculus.jpg|]s<br/>''Spheniscus mendiculus'' | |||
Bonner is a penguin and he mates with them. | |||
Image:Humboldt Penguin.jpg|] (''Spheniscus humboldti'') at the ] | |||
Bonner is a penguin and he mates with them. | |||
Image:Magellanic-penguin02.jpg|]<br/>''Spheniscus magellanicus'' | |||
Bonner is a penguin and he mates with them. | |||
</gallery> | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
== References == | |||
Bonner is a penguin and he mates with them. | |||
* '''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. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
* '''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. '']'' '''273''': 11-17. <small>{{doi|10.1098/rspb.2005.3260}}</small> | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
* '''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. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
* '''Bertelli''', Sara & '''Giannini''', Norberto P. (2005): A phylogeny of extant penguins (Aves: Sphenisciformes) combining morphology and mitochondrial sequences. ''Cladistics'' '''21'''(3): 209–239. <small>{{doi|10.1111/j.1096-0031.2005.00065.x}}</small> (HTML abstract) | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
* '''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. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
* '''Davis'''; Lloyd S. & '''Renner'''; M. (1995). ''Penguins'' . London: T & A D Poyser. <small>ISBN 0-7136-6550-5</small> | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
* '''Fain''', Matthew G. & '''Houde''', Peter (2004): Parallel radiations in the primary clades of birds. '']'' '''58'''(11): 2558-2573. <small>{{DOI|10.1554/04-235}}</small> | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
* '''Jadwiszczak''', Piotr (2006): Eocene penguins of Seymour Island, Antarctica: taxonomy. ''Polish Polar Research'' '''27'''(1), 3–62. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
* '''Ksepka''', Daniel T., Bertelli, Sara & Giannini, Norberto P. (2006): The phylogeny of the living and fossil Sphenisciformes (penguins). ''Cladistics'' '''22'''(5): 412–441. <small>{{doi|10.1111/j.1096-0031.2006.00116.x}}</small> (HTML abstract) | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
* '''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. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
* '''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. <small>{{doi|10.1111/j.1439-0469.2004.00291.x}}</small> | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
* '''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. <small>{{DOI|10.1093/molbev/msj124}}</small> | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
* '''Williams'''; Tony D. (1995). ''The Penguins - Spheniscidae'' . Oxford: Oxford University Press. <small>ISBN 0-19-854667-X</small> | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
===Footnotes=== | |||
Bonner is a penguin and he mates with them. | |||
<references /> | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
== External links == | |||
Bonner is a penguin and he mates with them. | |||
* | |||
Bonner is a penguin and he mates with them. | |||
* | |||
Bonner is a penguin and he mates with them. | |||
* | |||
Bonner is a penguin and he mates with them. | |||
* | |||
Bonner is a penguin and he mates with them. | |||
* | |||
Bonner is a penguin and he mates with them. | |||
* | |||
Bonner is a penguin and he mates with them. | |||
* | |||
Bonner is a penguin and he mates with them. | |||
* | |||
Bonner is a penguin and he mates with them. | |||
* | |||
Bonner is a penguin and he mates with them. | |||
* on the Internet Bird Collection | |||
Bonner is a penguin and he mates with them. | |||
* | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
{{Link FA|af}} | |||
Bonner is a penguin and he mates with them. | |||
{{Link FA|de}} | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
] | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. | |||
Bonner is a penguin and he mates with them. |
Revision as of 18:59, 13 March 2007
For other uses, see Penguin (disambiguation).
Penguins Temporal range: Paleocene-Recent | |
---|---|
Chinstrap Penguin, Pygoscelis antarctica | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Sphenisciformes Sharpe, 1891 |
Family: | Spheniscidae Bonaparte, 1831 |
Modern genera | |
|
Penguins (order Sphenisciformes, family Spheniscidae) are a group of aquatic, flightless birds living almost exclusively in the Southern Hemisphere.
The number of penguin species has been and still is a matter of debate. Depending on which authority is followed, biodiversity varies between 17 and 20 living species, all in the subfamily Spheniscinae. Some sources consider the White-flippered Penguin a separate Eudyptula species, while others treat it as a subspecies of the Little Penguin (e.g. Williams, 1995; Davis & Renner, 2003); the actual situation seems to be more complicated (Banks et al. 2002). Similarly, it is still unclear whether the Royal Penguin is merely a color morph of the Macaroni penguin. Also possibly eligible to be treated as a separate species is the Northern population of Rockhopper penguins (Davis & Renner, 2003). 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. Three species live in the temperate zone; one lives as far north as the Galápagos Islands (the Galápagos Penguin).
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 or the Blue Penguin), which stands around 40 cm tall (16 in) and weighs 1 kg (2.2 lb). Generally larger penguins retain heat better, and thus inhabit colder regions, while smaller penguins are found in temperate or even tropical climates (see also Bergmann's Rule). Some prehistoric species attained enormous sizes, becoming as high or as heavy as an adult human; see below for more.
Most penguins feed on krill, fish, squid, and other forms of sealife caught while swimming underwater. They spend half of their life on land and half in the oceans.
Penguins seem to have no fear of humans and have approached groups of explorers without hesitation. This is probably on account of there being no land predators in Antarctica or the nearby offshore islands that prey on or attack penguins. Instead, penguins are at risk at sea from predators such as the leopard seal.
A new study by MIT released in January of 2007, found that 80% of penguins were left handed. The findings concluded that penguins use their dominant flipper for everything from building nests to moving other penguins out of the way.
Anatomy
Penguins are superbly adapted to an aquatic life. Their wings have become flippers, useless for flight in the air. In the water, however, penguins are astonishingly agile. Within the smooth plumage a 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 - that is, they have a white underside and a dark (mostly black) upperside. This is for camouflage. A predator looking up from below (such as an orca or 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 (1870 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 allows them to conserve energy and move relatively fast at the same time.
Penguins have an excellent sense of hearing. Their eyes are adapted for underwater vision, and are their primary means of locating prey and avoiding predators; in air, conversely, they are nearsighted. Their sense of smell has not been researched so far.
They are able to drink salt water safely because their supraorbital gland filters excess salt from the bloodstream. The salt is excreted in a concentrated fluid from the nasal passages.
Mating habits
Some penguins mate for life, others for just one season. They generally raise a small brood, and the parents cooperate in caring for the clutch and for the young. During the cold season on the other hand the mates separate for several months to protect the egg. Usually, the male stays with the egg and keeps it warm, and the female goes out to sea and finds food so that when it comes home, the baby will have food to eat. Once the female comes back, they switch roles. 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. As the young grow, they assemble in large groups called crèches in some species, such as Emperor Penguins. There are some cases where penguins of the same sex do pair.
Systematics and evolution
Systematics
Updated after Marples (1962), Acosta Hospitaleche (2004), and Ksepka et al. (2006). See the gallery for images of most living species.
ORDER SPHENISCIFORMES
- Basal and unresolved taxa
- Waimanu - basal (Middle-Late Eocene)
- Sphenisciformes gen. et sp. indet. CADIC P 21 (Leticia Middle Eocene of Punta Torcida, Argentina: Clarke et al. 2003)
- Family Spheniscidae
- Subfamily 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)
- Nordenskjoeld's Giant Penguin, Anthropornis nordenskjoeldi
- Archaeospheniscus (Middle/Late Eocene - Late Oligocene)
- Delphinornis (Middle/Late Eocene ?- Early Oligocene of Seymour Island, Antarctica) - tentatively assigned to this subfamily
- Marambiornis (Late Eocene -? Early Oligocene of Seymour Island, Antarctica) - tentatively assigned to this subfamily
- Mesetaornis (Late Eocene -? Early Oligocene of Seymour Island, Antarctica) - tentatively assigned to this subfamily
- Palaeeudyptes (Middle/Late Eocene - Late Oligocene)
- Pachydyptes (Late Eocene)
- Platydyptes (Late Oligocene of New Zealand)
- Anthropodyptes (Middle Miocene) - tentatively assigned to this subfamily
- Subfamily Paraptenodytinae - Patagonian stout-legged penguins (fossil)
- Arthrodytes (San Julian Late Eocene/Early Oligocene - Patagonia Early Miocene of Patagonia, Argentina)
- Paraptenodytes (Early - Late Miocene/Early Pliocene)
- Subfamily Palaeospheniscinae - Patagonian slender-legged penguins (fossil)
- Eretiscus (Patagonia Early Miocene of Patagonia, Argentina)
- Palaeospheniscus (Early? - Late Miocene/Early Pliocene) - includes Chubutodyptes
- Subfamily Spheniscinae - Modern penguins
- Aptenodytes - Great penguins (2 species)
- Pygoscelis - Brush-tailed penguins (3 species)
- Eudyptula - Little penguins (2 species)
- Spheniscus - Banded penguins (4 species)
- Megadyptes - Yellow-eyed Penguin
- Eudyptes - Crested penguins (5-7 living species, possibly another one recently extinct)
- Not assigned to a subfamily (all fossil)
- 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)
- Korora (Late Oligocene of S Canterbury, New Zealand)
- Spheniscidae gen. et sp. indet (Late Oligocene/Early Miocene of Hakataramea, New Zealand)
- Pseudaptenodytes (Late Miocene/Early Pliocene)
- Marplesornis (Pliocene)
- Dege - possibly Spheniscinae
- Nucleornis - possibly Spheniscinae
- Subfamily Palaeeudyptinae - Giant penguins (fossil)
Taxonomy: Clarke et al. (2003) and Ksepka et al. (2006) apply the phylogenetic taxon Spheniscidae to what here is referred to as Spheniscinae. Furthermore, they restrict the phylogenetic taxon Sphenisciformes to flightless taxa, and establish (Clarke et al. 2003) the phylogenetic taxon Pansphenisciformes as equivalent to the Linnean taxon Sphenisciformes, 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 phylogeny is presently resolved, this seems spurious and in any case is confusing; the established Linnean system is thus followed here.
Evolution
The evolutionary history of penguins is by now fairly 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 taxonomy of many prehistoric forms still leaves much to be desired. A number of seminal articles dealing with penguin prehistory has been published since 2005 (Bertelli & Giannini 2005, Baker et al. 2006, Ksepka et al. 2006, Slack et al. 2006), and at least the evolution of the living genera can be considered resolved by now.
According to the comprehensive review of the available evidence by Ksepka et al. (2006), the basal penguins lived around the time of the Cretaceous-Paleogene extinction event somewhere in the general area of (southern) New Zealand and Byrd Land, Antarctica. Due to plate tectonics, these areas were at that time less than 1500 kilometers apart rather than the 4000 km of today. The last common ancestor of penguins and their sister clade can be roughly dated to the Campanian-Maastrichtian boundary, around 70-68 mya (Baker et al. 2006, Slack et al. 2006) 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 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 (see also Flightless Cormorant).
The oldest fossils
The oldest known fossil penguin species is Waimanu manneringi, which lived in the early Paleocene epoch of New Zealand, or about 62 mya (Slack et al. 2006). 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.
An unnamed fossil from Argentina proves that by the Bartonian (Middle Eocene), some 39-38 mya, primitive penguins had spread to South America and were in the process of expanding into Atlantic waters (Clarke et al. 2003).
"Palaeeudyptines"
During the Late Eocene and the Early Oligocene (40-30 mya), some lineages of gigantic penguins existed. Nordenskjoeld's Giant Penguin was the tallest, growing nearly 1.80 meters (6 feet) tall. The New Zealand Giant Penguin was 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 subfamily called Palaeeudyptinae. More recently, with new taxa being discovered and placed in the phylogeny if possible, it is becoming accepted that there were at least 2 major extinct lineages. One or two closely related ones occurred in Patagonia, and at least one other - which is or includes the paleeeudyptines as recognized today - occurred on most Antarctic and subantarctic coasts.
But size plasticity seems to have been great at this initial stage of penguin radiation: on Seymour Island, Antarctica, for example, around ten known species of penguins ranging from medium to huge size apparently coexisted some 35 mya during the Priabonian (Late Eocene) (Jadwiszczak 2006). It is not even known whether the gigantic palaeeudyptines constitute a monophyletic lineage, or whether gigantism was evolved independently in a much restricted Palaeeudyptinae and the Anthropornithinae - were they 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) (Ksepka et al. 2006).
In any case, the gigantic penguins had disappeared by the end of the Paleogene, around 25 mya. Interestingly, their decline and disappearance coincides 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 (Baker et al. 2006). A new lineage, the Paraptenodytinae which includes smaller but decidedly stout-legged forms, had already arisen in southernmost South America by that time. The early Neogene saw 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 biodiversity of our time.
Origin and systematics of modern penguins
Modern penguins consititute two undisputed clades and another two more basal genera with more ambiguous relationships (Bertelli & Giannini 2005). 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 (Baker et al. 2006). Presumedly diverging from other penguins around 40 mya (Baker et al. 2006), it seems that the Spheniscinae were for quite some time limited to their ancestral area, as the well-researched deposits of the Antarctic Peninsula and Patagonia have 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, they 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 habitat conditions. As the former genus, it seems to have diverged during the Bartonian, but the range expansion and radiation which lead to the present-day diversity probably did not occur until much later, around the Burdigalian stage of the Early Miocene, roughly 20-15 mya (Baker et al. 2006).
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 carotenoid coloration, and the former genus has a conspicuous banded head pattern; they are unique among living penguins in nesting in burrows. This group probably radiated eastwards with the Antarctic Circumpolar Current out of the ancestral range of modern penguins throughout the Chattian (Late Oligocene), starting approximately 28 mya (Baker et al. 2006). While the two genera separated during this time, the present-day diversity is the result of a Pliocene radiation, taking place some 4-2 mya (Baker et al. 2006).
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 (Baker et al. 2006).
It is most interesting to note that the geographical and temporal pattern or spheniscine evolution corresponds closely to two episodes of global cooling documented in the paleoclimatic record (Baker et al. 2006). 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 enabling the eastward expansion of Spheniscus to South America and eventually beyond (Baker et al. 2006).
Later, an interspersed period of slight warming was ended by the Middle Miocene Climate Transition, a sharp drop in global average temperature from 14 to 12 mya, and similar abrupt cooling events followed at 8 mya and 4 mya; by the end of the Tortonian, the Antarctic ice sheet was 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 adative 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 sequence datasets 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 of 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 Ciconiiformes (e.g. Slack et al. 2006) or to Procellariiformes (Baker et al. 2006) has been suggested. Some (e.g. Mayr 2005) 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 Pelecaniformes and 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.
Name
Penguin is thought by some to derive from the Welsh words pen (head) and gwyn (white), applied to the Great Auk, which had a conspicuous white patch between the bill and the eye (although its head was black), or from an island off Newfoundland known as "White Head" due to a large white rock. This may be, however, a false etymology created by Dr. John Dee in his book on Prince Madoc of Wales, supposedly one of the discoverers of America. By this Dee hoped to cement Queen Elizabeth I's claim, as a Tudor, to the New World. Penguins live nowhere near Newfoundland, nor do they generally have white heads, but they do look remarkably like Great Auks in general shape.
According to another theory, the original name was pen-wing, with reference to the rudimentary wings of both Great Auks and penguins. A third theory is that penguin comes from the Latin pinguis (fat). This has added credibility because the two other Germanic languages, Dutch 'pinguïn' and German, 'Pinguin', as well as the Russian 'пингвин' ('pingvin') all have the 'i' vowel as well. While it has been replaced by an 'e' in the English spelling, the "i" can still be heard. By simply looking at the word's pronunciation and comparing that to the Dutch, German, and Russian words, one could assume a common Latin root - after the first Germanic sound shift (500-200 BC) that makes a PIE 'p' into a 'f'. However, a Welsh 'i' is often sound-shifted to an 'e' in the English language, so a Welsh origin cannot be dismissed.
Penguins in popular culture
Main article: Penguins in popular culturePenguins are popular around the world, primarily for their unusually upright, waddling pace and (compared to other birds) lack of fear of humans. Their striking black and white plumage is often likened to a tuxedo suit and generates humorous remarks about the bird being "well dressed". Perhaps in reaction to this cutesy stereotype, fictional penguins are occasionally presented as grouchy or even sinister. Penguins have also been the subject of many books and documentary films.
Gallery of living species
-
Emperor Penguins
Aptenodytes forsteri -
King Penguins
Aptenodytes patagonicus -
Adelie penguins
Pygoscelis adeliae - Chinstrap Penguin (Pygoscelis antarctica) hunting for krill
-
Gentoo Penguin
Pygoscelis papua -
Southern Rockhopper Penguin
Eudyptes chrysocome -
Fiordland Penguin
Eudyptes pachyrhynchus -
Snares Penguin
Eudyptes robustus -
Macaroni Penguin
Eudyptes chrysolophus -
Yellow-eyed Penguin
Megadyptes antipodes -
Little Penguin or Fairy Penguin
Eudyptula minor -
African Penguin or Jackass Penguin Spheniscus demersus
African Penguin or Jackass Penguin
Spheniscus demersus -
Galapagos Penguins
Spheniscus mendiculus - Humboldt Penguin (Spheniscus humboldti) at the Milwaukee County Zoological Gardens
-
Magellanic Penguin
Spheniscus magellanicus
References
- 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. 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 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. 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. 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 PDF fulltext
- Jadwiszczak, Piotr (2006): Eocene penguins of Seymour Island, Antarctica: taxonomy. Polish Polar Research 27(1), 3–62. PDF fulltext
- 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 PDF fulltext
- 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 PDF fulltext Supplementary Material
- Williams; Tony D. (1995). The Penguins - Spheniscidae . Oxford: Oxford University Press. ISBN 0-19-854667-X
Footnotes
- "Animal Fact Sheets". Retrieved 2006-07-21.
- "Humboldt Penguin :: Saint Louis Zoo". Retrieved 2006-07-21.
- "African Penguins and Penguins of the World". Retrieved 2006-07-21.
- "Columbia News Service: June 10, 2002: They're in love. They're gay. They're penguins... And they're not alone". Retrieved 2006-07-21.
- "365gay.com: Gay Penguins Resist 'Aversion Therapy'". Retrieved 2006-07-21.
- The seemingly 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 uncertainities of the molecular clock used.
- Contra Baker et al. (2006).
- In fact, it is fairly likely that during the Bartonian, there was a near-synchronous split between the ancestors of Aptenodytes, Pygoscelis, and the common ancestor of all remaining genera (Baker et al. 2006).
External links
- penguinpage.net - Weblog covering ongoing research in NZ penguins
- Penguin information on 70South
- Gentoo penguin webcam from the Antarctic
- Information about penguins at pinguins.info
- PBS Nature: The World of Penguins
- Integrated Taxonomic Information System
- Seaworld Penguin Information
- Penguin Weblog
- Pictures Penguins
- Penguin Videos on the Internet Bird Collection
- Penguin World
Template:Link FA Template:Link FA
Categories: