47-845: Auks or alcids are a group of birds of the family Alcidae in the order Charadriiformes . The alcid family includes the murres , guillemots , auklets , puffins , and murrelets . The family contains 25 extant or recently extinct species that are divided into 11 genera. Auks are found throughout the Northern Hemisphere . Apart from the extinct great auk , all auks can fly, and are excellent swimmers and divers (appearing to "fly" in water), but their walking appears clumsy. Several species have different English names in Europe and North America. The two species known as "murres" in North America are called "guillemots" in Europe, and
94-682: A better sense of smell. A third stage of bird evolution starting with Ornithothoraces (the "bird-chested" avialans) can be associated with the refining of aerodynamics and flight capabilities, and the loss or co-ossification of several skeletal features. Particularly significant are the development of an enlarged, keeled sternum and the alula , and the loss of grasping hands. † Anchiornis † Archaeopteryx † Xiaotingia † Rahonavis † Jeholornis † Jixiangornis † Balaur † Zhongjianornis † Sapeornis † Confuciusornithiformes † Protopteryx † Pengornis Ornithothoraces † Enantiornithes Plover see
141-473: A definition similar to "all theropods closer to birds than to Deinonychus ", with Troodon being sometimes added as a second external specifier in case it is closer to birds than to Deinonychus . Avialae is also occasionally defined as an apomorphy-based clade (that is, one based on physical characteristics). Jacques Gauthier , who named Avialae in 1986, re-defined it in 2001 as all dinosaurs that possessed feathered wings used in flapping flight , and
188-442: A group called Paraves . Some basal members of Deinonychosauria, such as Microraptor , have features which may have enabled them to glide or fly. The most basal deinonychosaurs were very small. This evidence raises the possibility that the ancestor of all paravians may have been arboreal , have been able to glide, or both. Unlike Archaeopteryx and the non-avialan feathered dinosaurs, who primarily ate meat, studies suggest that
235-549: A long lifespan and slow reproduction. The earliest unequivocal fossils of auks are from the late Eocene , some 35 Mya. The genus Miocepphus , (from the Miocene , 15 Mya) is the earliest known from good specimens. Two very fragmentary fossils are often assigned to the Alcidae, although this may not be correct: Hydrotherikornis (Late Eocene ) and Petralca (Late Oligocene ). Most extant genera are known to exist since
282-589: A single egg, and they use the nesting site year after year. Some species, such as the Uria guillemots (murres), nest in large colonies on cliff edges; others, such as the Cepphus guillemots, breed in small groups on rocky coasts; and the puffins , auklets, and some murrelets nest in burrows. All species except the Brachyramphus murrelets are colonial. Traditionally, the auks were believed to be one of
329-406: A sister group, the order Crocodilia , contain the only living representatives of the reptile clade Archosauria . During the late 1990s, Aves was most commonly defined phylogenetically as all descendants of the most recent common ancestor of modern birds and Archaeopteryx lithographica . However, an earlier definition proposed by Jacques Gauthier gained wide currency in the 21st century, and
376-717: A time, sometimes for years, and rarely for life. Other species have breeding systems that are polygynous (one male with many females) or, rarely, polyandrous (one female with many males). Birds produce offspring by laying eggs which are fertilised through sexual reproduction . They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Many species of birds are economically important as food for human consumption and raw material in manufacturing, with domesticated and undomesticated birds being important sources of eggs, meat, and feathers. Songbirds , parrots, and other species are popular as pets. Guano (bird excrement)
423-429: Is harvested for use as a fertiliser. Birds figure throughout human culture. About 120 to 130 species have become extinct due to human activity since the 17th century, and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry. The first classification of birds
470-503: Is not considered a direct ancestor of birds, though it is possibly closely related to the true ancestor. Over 40% of key traits found in modern birds evolved during the 60 million year transition from the earliest bird-line archosaurs to the first maniraptoromorphs , i.e. the first dinosaurs closer to living birds than to Tyrannosaurus rex . The loss of osteoderms otherwise common in archosaurs and acquisition of primitive feathers might have occurred early during this phase. After
517-516: Is synonymous to Avifilopluma. † Scansoriopterygidae † Eosinopteryx † Jinfengopteryx † Aurornis † Dromaeosauridae † Troodontidae Avialae Based on fossil and biological evidence, most scientists accept that birds are a specialised subgroup of theropod dinosaurs and, more specifically, members of Maniraptora , a group of theropods which includes dromaeosaurids and oviraptorosaurs , among others. As scientists have discovered more theropods closely related to birds,
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#1732772975175564-535: Is used by many scientists including adherents to the PhyloCode . Gauthier defined Aves to include only the crown group of the set of modern birds. This was done by excluding most groups known only from fossils , and assigning them, instead, to the broader group Avialae, on the principle that a clade based on extant species should be limited to those extant species and their closest extinct relatives. Gauthier and de Queiroz identified four different definitions for
611-560: The Synthliboramphus murrelets should be split into a distinct tribe, as they appear more closely related to the Alcini; in any case, assumption of a closer relationship between the former and the true guillemots was only weakly supported by earlier studies. Of the genera, only a few species are placed in each. This is probably a product of the rather small geographic range of the family (the most limited of any seabird family), and
658-537: The Lari suborder, which otherwise contains gulls and similar birds. Judging from genetic data, their closest living relatives appear to be the skuas , with these two lineages separating about 30 million years ago (Mya). Alternatively, auks may have split off far earlier from the rest of the Lari and undergone strong morphological, but slow genetic evolution, which would require a very high evolutionary pressure , coupled with
705-669: The Tiaojishan Formation of China, which has been dated to the late Jurassic period ( Oxfordian stage), about 160 million years ago. The avialan species from this time period include Anchiornis huxleyi , Xiaotingia zhengi , and Aurornis xui . The well-known probable early avialan, Archaeopteryx , dates from slightly later Jurassic rocks (about 155 million years old) from Germany . Many of these early avialans shared unusual anatomical features that may be ancestral to modern birds but were later lost during bird evolution. These features include enlarged claws on
752-409: The least auklet , at 85 g (3 oz) and 15 cm (5.9 in), to the thick-billed murre , at 1 kg (2.2 lb) and 45 cm (18 in). Due to their short wings, auks have to flap their wings very quickly to fly. Although not to the extent of penguins, auks have largely sacrificed flight, and also mobility on land, in exchange for swimming ability; their wings are a compromise between
799-575: The only known living dinosaurs . Likewise, birds are considered reptiles in the modern cladistic sense of the term, and their closest living relatives are the crocodilians . Birds are descendants of the primitive avialans (whose members include Archaeopteryx ) which first appeared during the Late Jurassic . According to recent estimates, modern birds ( Neornithes ) evolved in the Late Cretaceous and diversified dramatically around
846-433: The 5.5 cm (2.2 in) bee hummingbird to the 2.8 m (9 ft 2 in) common ostrich . There are over 11,000 living species and they are split into 44 orders . More than half are passerine or "perching" birds. Birds have wings whose development varies according to species; the only known groups without wings are the extinct moa and elephant birds . Wings, which are modified forelimbs , gave birds
893-691: The AOS and BirdLife International 's Handbook of the Birds of the World separate the four members of genus Pluvialis as subfamily Pluvialinae. The IOC recognizes these 69 species of plovers, dotterels, and lapwings in family Charadriidae. They are distributed among 11 genera, some of which have only one species. This list is presented according to the IOC taxonomic sequence and can also be sorted alphabetically by common name and binomial. Plovers are found throughout
940-599: The Atlantic during the Pliocene. Auks also tend to be restricted to continental-shelf waters and breed on few oceanic islands. Hydotherikornis oregonus (Described by Miller in 1931), the oldest purported alcid from the Eocene of California, is actually a petrel (as reviewed by Chandler in 1990) and is reassigned to the tubenoses (Procellariiformes). A 2003 paper, "The Earliest North American Record of Auk (Aves: Alcidae) From
987-741: The Atlantic existed), with later movements across the Arctic Ocean. The flightless subfamily Mancallinae , which was apparently restricted to the Pacific Coast of southern North America and became extinct in the Early Pleistocene , is sometimes included in the family Alcidae under some definitions. One species, Miomancalla howardae , is the largest charadriiform of all time. The family contains 25 extant or recently extinct species that are divided into 11 genera. The extant auks (subfamily Alcinae) are broken up into two main groups -
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#17327729751751034-594: The Late Eocene of Central Georgia", reports a Late Eocene, wing-propelled, diving auk from the Priabonain stage of the Late Eocene. These sediments have been dated through Chandronian NALMA {North American Land Mammal Age}, at an estimate of 34.5 to 35.5 million years on the Eocene time scale for fossil-bearing sediments of the Clinchfield Formation, Gordon, Wilkinson County, Georgia. Furthermore,
1081-613: The Late Miocene or Early Pliocene (about 5 Mya). Miocene fossils have been found in both California and Maryland , but the greater diversity of fossils and tribes in the Pacific leads most scientists to conclude they first evolved there, and in the Miocene Pacific, the first fossils of extant genera are found. Early movement between the Pacific and the Atlantic probably happened to the south (since no northern opening to
1128-421: The Pliocene. See the genus accounts for prehistoric species. Bird Birds are a group of warm-blooded vertebrates constituting the class Aves ( Latin: [ˈaveːs] ), characterised by feathers , toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart , and a strong yet lightweight skeleton . Birds live worldwide and range in size from
1175-480: The ability to fly, although further evolution has led to the loss of flight in some birds , including ratites , penguins , and diverse endemic island species. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds , have further evolved for swimming. The study of birds is called ornithology . Birds are feathered theropod dinosaurs and constitute
1222-428: The appearance of Maniraptoromorpha, the next 40 million years marked a continuous reduction of body size and the accumulation of neotenic (juvenile-like) characteristics. Hypercarnivory became increasingly less common while braincases enlarged and forelimbs became longer. The integument evolved into complex, pennaceous feathers . The oldest known paravian (and probably the earliest avialan) fossils come from
1269-413: The best possible design for diving and the bare minimum needed for flying. This varies by subfamily, with the Uria guillemots (including the razorbill ) and murrelets being the most efficient under the water, whereas the puffins and auklets are better adapted for flying and walking. The feeding behaviour of auks is often compared to that of penguins; both groups are wing -propelled, pursuit divers. In
1316-509: The birds that descended from them. Despite being currently one of the most widely used, the crown-group definition of Aves has been criticised by some researchers. Lee and Spencer (1997) argued that, contrary to what Gauthier defended, this definition would not increase the stability of the clade and the exact content of Aves will always be uncertain because any defined clade (either crown or not) will have few synapomorphies distinguishing it from its closest relatives. Their alternative definition
1363-507: The case of Uria guillemots, 40 m (130 ft) for the Cepphus guillemots and 30 m (98 ft) for the auklets. Auks are pelagic birds, spending the majority of their adult lives on the open sea and going ashore only for breeding, although some species, such as the common guillemot , spend a great part of the year defending their nesting spot from others. Auks are monogamous, and tend to form lifelong pairs. They typically lay
1410-463: The earliest distinct charadriiform lineages due to their characteristic morphology , but genetic analyses have demonstrated that these peculiarities are the product of strong natural selection, instead; as opposed to, for example, plovers (a much older charadriiform lineage), auks radically changed from a wading shorebird to a diving seabird lifestyle. Thus today, the auks are no longer separated in their own suborder (Alcae), but are considered part of
1457-665: The earliest members of Aves, is removed from this group, becoming a non-avian dinosaur instead. These proposals have been adopted by many researchers in the field of palaeontology and bird evolution , though the exact definitions applied have been inconsistent. Avialae, initially proposed to replace the traditional fossil content of Aves, is often used synonymously with the vernacular term "bird" by these researchers. † Coelurus † Ornitholestes † Ornithomimosauria † Alvarezsauridae † Oviraptorosauria Paraves Most researchers define Avialae as branch-based clade, though definitions vary. Many authors have used
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1504-451: The first avialans were omnivores . The Late Jurassic Archaeopteryx is well known as one of the first transitional fossils to be found, and it provided support for the theory of evolution in the late 19th century. Archaeopteryx was the first fossil to display both clearly traditional reptilian characteristics—teeth, clawed fingers, and a long, lizard-like tail—as well as wings with flight feathers similar to those of modern birds. It
1551-402: The outermost half) can be seen in the evolution of maniraptoromorphs, and this process culminated in the appearance of the pygostyle , an ossification of fused tail vertebrae. In the late Cretaceous, about 100 million years ago, the ancestors of all modern birds evolved a more open pelvis, allowing them to lay larger eggs compared to body size. Around 95 million years ago, they evolved
1598-443: The periods of glacial advance and retreat that have kept the populations on the move in a narrow band of subarctic ocean. Today, as in the past, the auks are restricted to cooler northern waters. Their ability to spread further south is restricted as their prey hunting method, pursuit diving, becomes less efficient in warmer waters. The speed at which small fish (which along with krill are the auk's principal prey) can swim doubles as
1645-661: The plovers, dotterels, and lapwings of family Charadriidae have been distributed among several subfamilies, with Charadriinae including most of the species. The International Ornithological Congress (IOC) and the Clements taxonomy do not assign species to subfamilies. The South American Classification Committee of the American Ornithological Society (AOS) includes all of the species in Charadriinae. The North American Classification Committee of
1692-536: The previously clear distinction between non-birds and birds has become blurred. By the 2000s, discoveries in the Liaoning Province of northeast China, which demonstrated many small theropod feathered dinosaurs , contributed to this ambiguity. The consensus view in contemporary palaeontology is that the flying theropods, or avialans , are the closest relatives of the deinonychosaurs , which include dromaeosaurids and troodontids . Together, these form
1739-407: The region where auks live, their only seabird competition are cormorants (which are dive-powered by their strong feet). In areas where the two groups feed on the same prey, the auks tend to feed further offshore. Strong-swimming murres hunt faster, schooling fish, whereas auklets take slower-moving krill. Time depth recorders on auks have shown that they can dive as deep as 100 m (330 ft) in
1786-452: The same biological name "Aves", which is a problem. The authors proposed to reserve the term Aves only for the crown group consisting of the last common ancestor of all living birds and all of its descendants, which corresponds to meaning number 4 below. They assigned other names to the other groups. Lizards & snakes Turtles Crocodiles Birds Under the fourth definition Archaeopteryx , traditionally considered one of
1833-551: The second toe which may have been held clear of the ground in life, and long feathers or "hind wings" covering the hind limbs and feet, which may have been used in aerial maneuvering. Avialans diversified into a wide variety of forms during the Cretaceous period. Many groups retained primitive characteristics , such as clawed wings and teeth, though the latter were lost independently in a number of avialan groups, including modern birds (Aves). Increasingly stiff tails (especially
1880-931: The sediments containing this unabraded portion of a left humerus (43.7 mm long) are tropical or subtropical as evidenced by a wealth of warm-water shark teeth, palaeophied snake vertebrae, and turtles. Rhinoceros auklet Tufted puffin Horned puffin Atlantic puffin Cassin's auklet Least auklet Parakeet auklet Whiskered auklet Crested auklet Ancient murrelet Japanese murrelet Craveri's murrelet Guadalupe murrelet Scripps's murrelet Long-billed murrelet Marbled murrelet Kittlitz's murrelet Black guillemot Spectacled guillemot Pigeon guillemot Thick-billed murre Common murre Little auk † Great auk Razorbill Biodiversity of auks seems to have been markedly higher during
1927-831: The species called little auk in Europe is referred to as dovekie in North America. The word "auk" / ɔː k / is derived from Icelandic álka and Norwegian alka or alke from Old Norse ālka from Proto-Germanic * alkǭ (sea-bird, auk). The family name Alcidae comes from the genus Alca given by Carl Linnaeus in 1758 for the razorbill ( Alca torda ) from the Norwegian word alke . Auks are superficially similar to penguins , having black-and-white colours, upright posture, and some of their habits. Nevertheless, they are not closely related to penguins, but rather are believed to be an example of moderate convergent evolution . Auks are monomorphic (males and females are similar in appearance). Extant auks range in size from
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1974-406: The table Plovers ( / ˈ p l ʌ v ər / PLUV -ər , also US : / ˈ p l oʊ v ər / PLOH -vər ) are members of a widely distributed group of wading birds of family Charadriidae . The term "plover" applies to all the members of the family, though only about half of them include it in their name. The taxonomy of family Charadriidae is unsettled. At various times
2021-490: The temperature increases from 5 to 15 °C (41 to 59 °F), with no corresponding increase in speed for the bird. The southernmost auks, in California and Mexico, can survive there because of cold upwellings . The current paucity of auks in the Atlantic (six species), compared to the Pacific (19–20 species) is considered to be because of extinctions to the Atlantic auks; the fossil record shows many more species were in
2068-600: The time of the Cretaceous–Paleogene extinction event 66 million years ago, which killed off the pterosaurs and all non- ornithuran dinosaurs. Many social species preserve knowledge across generations ( culture ). Birds are social, communicating with visual signals, calls, and songs , and participating in such behaviour as cooperative breeding and hunting, flocking , and mobbing of predators. The vast majority of bird species are socially (but not necessarily sexually) monogamous , usually for one breeding season at
2115-410: The usually high-billed puffins (tribe Fraterculini) and auklets (tribe Aethiini), as opposed to the more slender-billed murres and true auks (tribe Alcini), and the murrelets and guillemots (tribes Brachyramphini and Cepphini). The tribal arrangement was originally based on analyses of morphology and ecology . mtDNA cytochrome b sequences , and allozyme studies confirm these findings except that
2162-481: The world, with the exception of the Sahara and the polar regions , and are characterised by relatively short bills. They hunt by sight, rather than by feel as longer-billed waders like snipes do. They feed mainly on insects, worms or other invertebrates, depending on the habitat, which are obtained by a run-and-pause technique, rather than the steady probing of some other wader groups. Plovers engage in false brooding,
2209-466: Was developed by Francis Willughby and John Ray in their 1676 volume Ornithologiae . Carl Linnaeus modified that work in 1758 to devise the taxonomic classification system currently in use. Birds are categorised as the biological class Aves in Linnaean taxonomy . Phylogenetic taxonomy places Aves in the clade Theropoda as an infraclass or a subclass, more recently a subclass. Aves and
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