Birds (Latin, Spanish, Portuguese, Italian: Ave, German: Vogel, English: Bird, French: Oiseau) are two-winged amphibians. Although some insects and bats have wings, only birds have feathers. There are about 10,000 species of birds in the world. Thus all living birds belong to the subclass Neornithis. The bird class (Aves) is divided into 23 classes, 142 genera, 2056 genera and 9602 species. [2] However, new species are constantly being discovered and new species are being identified by dividing some old species. Fossils found so far indicate that the birds appeared in the Jurassic period, about 160 million years ago. According to paleontologists, birds are the only offspring of the four-limbed dinosaur after the extinction of the Cretaceous-Paleogene 65 million years ago. Among the living birds, the bee hummingbird is the smallest (only 5 centimeters or 2 inches) and the ostrich is the largest (2.75 meters or 9 feet).
Birds
Periodic range: End-Jurassic stage-present, 15.0–0 crore
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Scientific Classification World: Animal World: Cordataupparva: Vertebrate / Vertibrata Category: Birds / Avis
Linnaeus, 1857 [1] subcategory
Archaeornithes *
Enantiornithes
Hesperornithes
Ichthyornithes
Neornithes
See the article for more information
Birds like fish, amphibians, reptiles and mammals are also vertebrates. The main features of modern day birds are feathers, toothless beak, hard-shelled eggs by which they leave their offspring, four-chambered heart, high cellular biochemical rate, light but strong bones, etc.