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The evolution of birds began in the Jurassic Period, with the earliest birds derived from a clade of theropod dinosaurs named Paraves. [1] Birds are categorized as a biological class , Aves. For more than a century, the small theropod dinosaur Archaeopteryx lithographica from the Late Jurassic period was considered to have been the earliest bird.
End Ordovician: 440 million years ago, 86% of all species lost, including graptolites; Late Devonian: 375 million years ago, 75% of species lost, including most trilobites; End Permian, The Great Dying: 251 million years ago, 96% of species lost, including tabulate corals, and most trees and synapsids
This is a collection of lists of mammal gestation period estimated by experts in their fields. The mammals included are only viviparous (marsupials and placentals) as some mammals, which are monotremes (including platypuses and echidnas) lay their eggs. A marsupial has a short gestation period, typically shorter than placental.
Egg incubation is the process by which an egg, of oviparous (egg-laying) animals, develops an embryo within the egg, after the egg's formation and ovipositional release. Egg incubation is done under favorable environmental conditions, possibly by brooding and hatching the egg.
Parrots have featured in human writings, story, art, humor, religion, and music for thousands of years, such as Aesop's fable "The parrot and the cat", [127] the mention "The parrot can speak, and yet is nothing more than a bird" in The Book of Rites of Ancient China, [128] the Masnavi by Rumi of Persia in 1250 "The Merchant and the Parrot". [129]
The sun conure was one of the many species originally described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae. [2] As Linnaeus did with many of the parrots he described, he placed this species in the genus Psittacus, but it has since been moved to the widely accepted Aratinga, which contains a number of similar New World species, while Psittacus is now restricted to the ...
The common ancestor of the kākāpō and the two Nestor species diverged 27–40 million years ago. [ 24 ] Earlier ornithologists felt that the kākāpō might be related to the ground parrots and night parrot of Australia due to their similar colouration, but this is contradicted by molecular studies; [ 25 ] rather, the cryptic colour seems to ...
Bird eggs are laid by the females and range in quantity from one (as in condors) to up to seventeen (the grey partridge). Clutch size may vary latitudinally within a species. Some birds lay eggs even when the eggs have not been fertilized; it is not uncommon for pet owners to find their lone bird nesting on a clutch of infertile eggs, which are ...