The original known bird is the Late Jurassic Archaeopteryx. Most paleontologists regard birds as the only clad of dinosaurs to have survived the Cretaceous Tertiary destruction event.
Modern birds are characterized by a beak with no teeth, feathers, the laying of hard shelled eggs, a high metabolic rate, a four chambered heart, and a lightweight but strong skeleton. All birds have forelimbs customized as wings and most of these species can fly, with some exceptions including ratites, penguins, and a number of varied endemic island species. They have exclusive digestive and respiratory systems that are highly modified for flight. Some birds, particularly corvids and parrots, are among the cleverest types of species.
Many birds undertake long distance yearly migrations, and many more do shorter irregular movements. Birds are social. They converse using visual signals and through calls and songs. They also contribute in social behaviors including supportive breeding and hunting, flocking, and mobbing of predators. The enormous mass of bird species is socially monogamous, usually for one breeding season at a time, sometimes for years, but seldom for life. Other types of species of birds have breeding systems that are polygynous, many females or, rarely, polyandrous many males. Eggs are typically laid in a nest and incubated by the parents.
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Birds belonging to the class Aves are bipedal, winged, endothermic and warm blooded. Birds are vertebrate types of animals that lay eggs. There are around 10,000 living types of species of birds making them the most numerous vertebrates. These types of animal species engage ecosystems across the globe. From the Arctic to the Antarctic these birds are found. Birds range in size from 5 cm Bee Hummingbird to the 3 m Ostrich. The fossil evidence indicates that birds evolved during the Jurassic period.
Birds belonging to the class Aves are bipedal, winged, endothermic and warm blooded. Birds are vertebrate types of animals that lay eggs. There are around 10,000 living types of species of birds making them the most numerous vertebrates. These types of animal species engage ecosystems across the globe. From the Arctic to the Antarctic these birds are found. Birds range in size from 5 cm Bee Hummingbird to the 3 m Ostrich. The fossil evidence indicates that birds evolved during the Jurassic period.
