Birds..

Birds are a group of warm-blooded vertebrates constituting the class Aves, characterized 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 the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft) ostrich. There are about ten thousand living species, more than half of which 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 evolved from forelimbs, gave birds 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.

Birds
Temporal range:
Early Cretaceous (Aptian) – Present,[1] 121–0 Ma PreꞒꞒOSDCPTJKPgNScientific classificationKingdom:AnimaliaPhylum:ChordataClade:SauropsidaClade:AvemetatarsaliaClade:OrnithuraeClass:Aves
Linnaeus, 1758[2]Extant orders and temporal rangeSee orders* Infraclass Palaeognathae

• Superorder Struthionimorphae

  • Struthioniformes (Ostrichs) – 58?–0 Mya, Late Paleocene?–Present

  • Superorder Notopalaeognathae

    • Rheiformes (Rheas) – 56–0 Mya, Late Paleocene–Present

    • Tinamiformes (Tinamous) – 10–0 Mya, Middle Miocene–Present

    • Casuariiformes (Casowaries and Emus) – 58.7–0 Mya, Late Paleocene–Present

    • Apterygiformes (Kiwis) – 23.03–0 Mya, Early Miocene–Present

• Infraclass Neognathae

  • Superorder Galloanserae

    • Galliformes (Gamebirds) – 45–0 Mya, Middle Eocene–Present

    • Anseriformes (Waterfowl) – 71–0 Mya, Late Cretaceous (Maastrichtian)–Present

  • Superorder Neoaves

    • Phoenicopteriformes (Flamingos) – 50–0 Mya, Early Eocene–Present

    • Podicipediformes (Grebes) – 25–0 Mya, Late Oligocene–Present

    • Columbiformes (Pigeons and doves) – 23.03–0 Mya, Early Miocene–Present

    • Mesitornithiformes (Mesites) – No fossil records

    • Pterocliformes (Sandgrouse) – 33.9–0 Mya, Late Oligocene–Present

    • Apodiformes (swifts, treeswifts and hummingbirds) – 52–0 Mya, Early Eocene–Present

    • Caprimulgiformes (Nightjars, nighthawks, potoos, oilbirds, frogmouths and owlet-nightjars) – 59.2–0 Mya, Middle Paleocene–Present

    • Cuculiformes (Cuckoos, anis, etc) – 34–0 Mya, Late Miocene–Present

    • Otidiformes (Bustards, floricans, etc) – 13–0 Mya, Middle Miocene–Present

    • Musophagiformes (Turacos and go-away-birds) – 24–0 Mya, Late Oligocene–Present

    • Opisthocomiformes (Hoatzin) – 33.9–0 Mya, Late Eocene–Present

    • Gruiformes (Cranes, crakes, rails, wood-rails, fluftais, gallinules, limpkins, trumpeters, finfoots and sungrebes) – 66–0 Mya, Late Cretaceous (Maastrichtian)–Present

    • Charadriiformes (Plovers, crab plovers, lapwings, seagulls, puffins, auks, sandipipers, buttonquails, stilts, avocets, ibisbills, woodcocks, skuas, etc) – 75–0 Mya, Late Cretaceous (Campanian)–Present

    • Gaviiformes (Loons) – 70–0 Mya, Late Cretaceous (Maastrichtian)–Present

    • Procellariiformes (petrels, storm petrels, albatrosses and diving petrels) – 33.9–0 Mya, Early Oligocene–Present

    • Sphenisciformes (penguins) – 62–0 Mya, Early Paleocene–Present

    • Ciconiiformes (storks, openbills and jabirus) – 30–0 Mya, Early Oligocene–Present

    • Suliformes (boobies, gannets, frigatebirds, cormorants, shags and anhingas) – 90–0 Mya, Late Cretaceous (Turonian)–Present

    • Pelecaniformes (pelicans, ibises, shoebills, egrets, herons, etc) – 66–0 Mya, Late Cretaceous (Maastrichtian)–Present

    • Eurypygiformes (sunbitterns and kagu) – 56–0 Mya, Late Paleocene–Present

    • Phaethontiformes (tropicbirds) – 58.7–0 Mya, Late Paleocene–Present

    • Cathartiformes (New World vultures) – 41–0 Mya, Middle Eocene–Present

    • Accipitriformes (eagles, Old World vultures, secretary-birds, hawks, harriers, etc) – 47–0 Mya, Late Eocene–Present

    • Strigiformes (owls) – 30–0 Mya, Early Oligocene–Present

    • Coliiformes (mousebirds) – ~65–0 Mya, Early Paleocene–Present

    • Leptosomiformes (cuckoorollers) – No fossil record

    • Trogoniformes (trogons and quetzals) – 49–0 Mya, Early Eocene–Present

    • Bucerotiformes (hornbills, hoopoes and wood-hoopoes) – ~40–0 Mya, Middle Eocene–Present

    • Coraciiformes (rollers, bee eaters, todys, kingfishers, etc) – 41.2–0 Mya, Middle Eocene–Present

    • Piciformes (woodpeckers, flickers, toucans, aracaris, motmots, etc) – 56–0 Mya, Early Eocene–Present

    • Cariamiformes (seriema) – 66–0 Mya, Late Cretaceous (Maastrichtian)–Present

    • Falconiformes (falcons and caracaras) – 50–0 Mya, Early Eocene–PPrese