English: Pavo cristatus Linnaeus, 1758 - tail feather of the common peafowl (male)

Birds are small to large, warm-blooded, egg-laying, feathered, bipedal vertebrates capable of powered flight (although some are secondarily flightless). Many scientists characterize birds as dinosaurs, but this is consequence of the physical structure of evolutionary diagrams. Birds aren’t dinosaurs. They’re birds. The logic & rationale that some use to justify statements such as “birds are dinosaurs” is the same logic & rationale that results in saying “vertebrates are echinoderms”. Well, no one says the latter. No one should say the former, either.

However, birds are evolutionarily derived from theropod dinosaurs. Birds first appeared in the Triassic or Jurassic, depending on which avian paleontologist you ask. They inhabit a wide variety of terrestrial and surface marine environments, and exhibit considerable variation in behaviors and diets.

The long, elaborate, colorful tail feathers of the peacock (= male peahen) are the evolutionary result of sexual selection, whereby physical or behavioral features are selected for based on their relative attractiveness to the opposite sex.

Classification: Animalia, Chordata, Vertebrata, Aves, Galliformes, Phasianidae