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Birds
The ability to fly is undoubtedly what has helped the success of birds the most, and their characteristics show this. Feathers keep birds warm and allow them to fly, and their warm-bloodedness lets them stay aloft no matter what the temperature is. Their hollow, reinforced bones, lack of teeth, and excretory system are all attempts to stay as light as possible to make flight easier, while the enormous chest muscles provide the power they need to fly. Nine thousand species of birds are known, many of which are in the order Passeriformes (song birds, such as sparrows and warblers). Other important orders include the Charadriiformes (shore birds), Anseriformes (geese and ducks), Falconiformes (falcons, hawks and eagles), Galliformes (chickens and turkeys), and many more orders. Page 1 Songbirds (order Passeriformes) Page 2 Shorebirds (order Charadriiformes) Page 3 Other birds
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Birds
first appeared 150 million years ago, branching off from the dinosaurs;
technically, they are now the only living dinosaurs! Like the mammals,
the number of bird species began to increase dramatically after the extinction
of the rest of the dinosaurs, and there are currently twice as many bird
species as mammal species. 