Bird
Birds (class Aves) are feathered, winged, bipedal, endothermic (warm-blooded), egg-laying, vertebrate animals. With around 10,000 living species, they are the most speciose class of tetrapod vertebrates. All present species belong to the subclass Neornithes, and inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from the 5 cm (2 in) Bee Hummingbird to the 2.75 m (9 ft) Ostrich. The fossil record indicates that birds emerged within theropod dinosaurs during the Jurassic period, around 160 million years (Ma) ago. Paleontologists regard birds as the only clade of dinosaurs to have survived the Cretaceous–Paleogene extinction event 65.5 Ma (million years) ago.
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Famous quotes containing the word bird:
“Mr. Bok is giving the bird sanctuary as a tract of land at this place. He is dedicating it as a bird sanctuary and putting up these bells to interest the birds in music.”
—Calvin Coolidge (1872–1933)
“Then the little Hiawatha
Learned of every bird its language,
Learned their names and all their secrets,”
—Henry Wadsworth Longfellow (1809–1882)
“Nor bird nor beast
Could make me wish for anything this day,
Being old, but that the old alone might die,
And that would be against God’s Providence.”
—William Butler Yeats (1865–1939)