Birds are a group of warm-blooded vertebrates that form the aviens and have feathers, toothless beaked jaws, hard-shell egg laying, high metabolic rate, four-chamber heart, strong and light It features a skeleton. Birds are found all over the world and range in size from a 5.5 cm (2.2 in) hummingbird to a 2.8 m (9 ft 2 in) ostrich. There are about 10,000 living species, more than half of which are passerine or "sedentary" birds. Birds have wings, the development of which depends on the species. The only known wingless groups are the extinct MOA and elephant birds. Wings with modified forelimbs gave birds the ability to fly, but further evolution lost the ability to fly in some birds, including raptors, penguins, and some endemic island species. . Birds' digestive and respiratory systems are also uniquely adapted for flight. Birds in aquatic environments, especially seabirds and some waterfowl, have evolved to swim.
Birds are feathered theropod dinosaurs and the only known living dinosaurs. Similarly, birds are considered reptiles in the modern taxonomic sense, and their closest extant relatives are crocodiles. Birds are descendants of primitive birds (including Archeopteryx) that first appeared in China about 160 million years ago. DNA evidence suggests that modern birds (Neornithes) evolved in the middle to late Cretaceous and diversified dramatically around the time of the Cretaceous-Paleogene extinction event 6600 years ago, leading to pterosaurs and all modern birds. Killed a non-avian dinosaur .
Many social species transmit knowledge across generations, which is considered a cultural form. Birds are sociable, communicating through visual cues, vocalizations, and songs, and participate in communal breeding, hunting, grazing, and predator flocks. Most birds are socially monogamous, usually her one breeding season at a time, sometimes for years, rarely for life. is not. Other species have polygamous (one male and many females) or rarely polygamous (one female and many males) reproductive systems. Birds produce offspring by laying fertilized eggs through reproduction. They are usually kept in nests and hatched by their parents. Most birds spend an extended period of time in parental care after hatching.
Many species of birds are economically important as food for human consumption and as raw materials for manufacturing, and domestic and non-domesticated birds are important supplies of eggs, meat and feathers. source. Songbirds, parrots and other species are popular pets. Guano (bird droppings) is harvested for use as fertilizer. Birds appear throughout human culture. Since the 17th century, 120 to 130 species have become extinct due to human activity, and hundreds more before then. About 1,200 bird species are threatened with extinction due to human activity, but efforts are being made to protect them. Recreational bird watching is an important part of the ecotourism industry.
Evolution and taxonomy
The first taxonomy of birds was developed in his 1676 book Ornithologiae by Francis Willughby and John Ray. Carl Linnaeus revised this work in his 1758 and developed the taxonomic classification system now in use. Birds are classified as the biological class of birds in Linnaean taxonomy. Phylogenetically, birds are classified as theropods.
You must be logged in to post a comment.