Changes

Almost all evolutionary biologists, with rare exceptions, believe that birds are the only extant group of dinosaurs, a branch of the theropods, which included ''Velociraptor'' and ''Deinonychus''. This view is disputed by [[creationism|creationists]], and also by a few prominent evolutionary biologists, including Storrs L. Olson, Curator of Birds at the [[National Museum of Natural History]] at the [[Smithsonian Institution]], who said: {{QuoteBox|The idea of feathered dinosaurs and the theropod origin of birds is being actively promulgated by a cadre of zealous scientists acting in concert with certain editors at Nature and National Geographic who themselves have become outspoken and highly biased proselytizers of the faith. Truth and careful scientific weighing of evidence have been among the first casualties in their program, which is now fast becoming one of the grander scientific hoaxes of our age—the paleontological equivalent of cold fusion.<ref>Olson, Storrs L., [http://creationontheweb.com/content/view/3385/ Open letter], 1st November, 1999.</ref>}}

Almost all evolutionary biologists, with rare exceptions, believe that birds are the only extant group of dinosaurs, a branch of the theropods, which included ''Velociraptor'' and ''Deinonychus''. This view is disputed by [[creationism|creationists]], and also by a few prominent evolutionary biologists, including Storrs L. Olson, Curator of Birds at the [[National Museum of Natural History]] at the [[Smithsonian Institution]], who said: {{QuoteBox|The idea of feathered dinosaurs and the theropod origin of birds is being actively promulgated by a cadre of zealous scientists acting in concert with certain editors at Nature and National Geographic who themselves have become outspoken and highly biased proselytizers of the faith. Truth and careful scientific weighing of evidence have been among the first casualties in their program, which is now fast becoming one of the grander scientific hoaxes of our age—the paleontological equivalent of cold fusion.<ref>Olson, Storrs L., [http://creationontheweb.com/content/view/3385/ Open letter], 1st November, 1999.</ref>}}

Since Olsen's open letter was published in 1999, however, numerous theropod fossils with clear evidence of feathers have been discovered<ref>Göhlich, U.B., and Chiappe, L.M. (2006). "A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago." Nature, 440: 329-332</ref>, with the result that there is now little doubt about the close relationship of birds, as extant dinosaurs, to the extinct theropod dinosaurs. Birds appear to have split from other dinosaur lineages sometime before the mid-Jurassic, 155-150 million years ago.

Since Olsen's open letter was published in 1999, however, numerous theropod fossils with clear evidence of feathers have been discovered<ref>Göhlich, U.B., and Chiappe, L.M. (2006). "A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago." Nature, 440: 329-332</ref>. This and other evidence means there is now little doubt about the close relationship of birds, as extant dinosaurs, to the extinct theropod dinosaurs. Birds appear to have split from other dinosaur lineages sometime before the mid-Jurassic, 155-150 million years ago.

=== Taxonomy ===

=== Taxonomy ===

The conventional [[Linnaean taxonomy]] places birds in the Class Aves within the Subphylum [[Vertebrate|Vertebrata]]. [[Reptilia]], the conventional Class of reptiles, includes [[crocodile]]s and relatives, [[lizard]]s and [[snake]]s, [[turtle]]s, and the [[tuatara]]. However, as birds are now believed to be [[dinosaur]]s, they should be grouped with [[archosaur]]s, including the extant crocodiles and the extinct [[pterosaur]]s. Hence the conventional classification does not reflect the current state of evolutionary biology. [[Zoology|Zoologists]] continue to use Class Aves as the taxonomic group of birds but recognise that it is a sub-group of the Superorder Dinosauria, which in turn is a member of the Archosauria, including crocodiles and the extinct pterosaurs. The higher classification of reptiles (including birds) is not fully resolved but a common view is that current evidence indicates that the archosaurs (including birds) are a sister group of the lepidosaurs, which include lizards, snakes, the tuatara, and the extinct [[mosasaur]]s and [[plesiosaur]]s.<ref>Benton, 2004. Vertebrate Paleontology</ref>

The conventional [[Linnaean taxonomy]] places birds in the Class Aves within the Subphylum [[Vertebrate|Vertebrata]]. [[Reptilia]], the conventional Class of reptiles, includes [[crocodile]]s and relatives, [[lizard]]s and [[snake]]s, [[turtle]]s, and the [[tuatara]]. However, birds and other, extinct [[dinosaur]]s should be grouped with [[archosaur]]s, along with the extant crocodiles and the extinct [[pterosaur]]s. Hence the conventional classification does not reflect the current state of evolutionary biology.

 

[[Zoology|Zoologists]] continue to use Class Aves as the taxonomic group of birds but recognise that it is a sub-group of the Superorder Dinosauria, which in turn is a member of the group Archosauria, including crocodiles and pterosaurs. The higher classification of reptiles (including birds) is not fully resolved but a common view is that current evidence indicates that the archosaurs (including birds) are a sister group of the lepidosaurs, which include lizards, snakes, the tuatara, and the extinct [[mosasaur]]s and [[plesiosaur]]s.<ref>Benton, 2004. Vertebrate Paleontology</ref>

===Evolution of flight===

===Evolution of flight===