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bird

Birds (Aves) are a group of endothermic vertebrates, 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 the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft) ostrich. They rank as the world’s most numerically-successful class of tetrapods, with approximately ten thousand living species, more than half of these being passerines, sometimes known as perching birds. Birds have wings which are more or less developed depending on the 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 flightless birds, including ratites, penguins, and diverse endemic island species of birds. 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. Reverse genetic engineering and the fossil record both demonstrate that birds are modern feathered dinosaurs, having evolved from earlier feathered dinosaurs within the theropod group, which are traditionally placed within the saurischian dinosaurs. The closest living relatives of birds are the crocodilians. Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period, around 170 million years ago.
pets and animals - beautiful animals and even more beautiful
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pets and animals

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pets and animals - beautiful animals and even more beautiful
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pets and animals

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pets and animals - beautiful animals and even more beautiful
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pets and animals

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pets and animals - beautiful animals and even more beautiful
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pets and animals

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pets and animals - beautiful animals and even more beautiful
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pets and animals

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pets and animals - beautiful animals and even more beautiful
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pets and animals

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pets and animals - beautiful animals and even more beautiful
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pets and animals

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pets and animals - beautiful animals and even more beautiful
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pets and animals

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pets and animals - beautiful animals and even more beautiful
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pets and animals

Added year ago by żaba

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pets and animals - beautiful animals and even more beautiful
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pets and animals

Added year ago by żaba

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pets and animals - beautiful animals and even more beautiful
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pets and animals

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134

pets and animals - beautiful animals and even more beautiful
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pets and animals

Added year ago by żaba

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pets and animals - beautiful animals and even more beautiful
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pets and animals

Added year ago by żaba

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pets and animals - beautiful animals and even more beautiful
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pets and animals

Added year ago by żaba

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pets and animals - beautiful animals and even more beautiful
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pets and animals

Added year ago by żaba

46

pets and animals - beautiful animals and even more beautiful
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pets and animals

Added year ago by żaba

31

pets and animals - beautiful animals and even more beautiful
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pets and animals

Added year ago by żaba

28

pets and animals - beautiful animals and even more beautiful
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pets and animals

Added year ago by żaba

9

pets and animals - beautiful animals and even more beautiful
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pets and animals

Added year ago by żaba

33

blue bird - heavenly bird, blue bird
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blue bird

Added year ago by żaba

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koliberki - hummingbirds while eating
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koliberki

Added year ago by żaba

52

lovely animals - bird on a snowy branch
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lovely animals

Added year ago by Basiunia

40

lovely animals - a bird on a frosted branch
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lovely animals

Added year ago by Basiunia

25

duckling flower - a flower that looks like ducklings
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duckling flower

Added year ago by żaba

22

tired duckling - I got tired very much and I need to rest
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tired duckling

Added year ago by reniulek

97

Cottage on the river - colorful puzzle jigsaw
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Cottage on the river

Added year ago by andi

85 1

lovely animals - white bird's head
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lovely animals

Added year ago by Basiunia

26 1

lovely animals - colorful feathers have this bird
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lovely animals

Added year ago by Basiunia

33

Autumn leaves - colorful puzzle jigsaw
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Autumn leaves

Added year ago by andi

62

Landscape - colorful landscape over the water
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Landscape

Added year ago by andi

336

Winter in painting - winter jigsaw puzzle
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Winter in painting

Added year ago by andi

526

lovely animals - bird with a rooster on his head
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lovely animals

Added year ago by Basiunia

65

lovely animals - colorful birds on the branch
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lovely animals

Added year ago by Basiunia

107

Penguins - at least 25 characters
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Penguins

Added year ago by tatiana

24