Sauropsida
The sauropsides gather the Oiseau X, all the current Reptile S and a part only of the fossil reptiles. It is today a group Monophylétique animals which is the Groupe brother Synapside S, i.e. of the Mammifère S, with which they form the taxon Amniote S.
The oldest known fossils of the sauropsides , clearly distinguished from the mammals, are gone back to approximately -315 My. The sauropsides , mainly the Dinosaur S, formed the greatest part of the animals of big size to the Mesozoic , until the transition Cretaceous-Tertiary sector there is 65 My. After this crisis, the mammals recovered the corresponding ecological niches, but not those of the birds which them also diversified.
The Reptile S with the direction running, i.e. without the birds, form a group Paraphylétique which, consequently is not relevant to evaluate the degrees of relationship between these species. The use of this term reptiles implies for example, which any reptile is closer to another reptile than of a bird, whereas it is faux : the Crocodile S for example are closer to the Oiseau X than of the Lézard S.
The group of the sauropsides on the other hand, being Monophylétique, indicates well that all the animals which form part of it have the same exclusive family ties, and does not prejudge various degrees of relationship between species inside this group (the term sauropside does not indicate if the Crocodile is closer to the Oiseau or the Lézard, and thus, any more error does not induce). For those which study the evolution, the term reptiles thus tends to include the birds, or with being to replace by the term sauropsides .
Phylogeny
Sauropsida |-- Anapsida | |-- Mesosauridae (extinct) | `-- Parareptilia | |-- Millerettidae (extinct) | |-- Bolosauridae (extinct) | `-- Procolophonomorpha | |-- Procolophonia | | |-- Procolophonidae (extinct) | | `-- Pareiasaur idae (extinct) | `? - Testudines (tortoises) `-- Eureptilia |-- Captorhinidae (extinct) `-- Romeriida |-- Protorothyrididae (extinct) `-- Diapsida |-- Araeoscelidia (extinct) |-- Avicephala (extinct) `-- Neodiapsida |? - Younginiformes (extinct) `--+-- Lepidosauromorpha | |? - Euryapsida | | |? - Sauropterygia (extinct) | | `? - Ichthyopterygia (extinct) | `-- Lepidosauriformes | `-- Lepidosauria | |-- Sphenodontida (including the Tuatara S) | `-- Squamata (including the Lizard S, Mosasaure S and the Snake S) `-- Archosauromorpha |? - Choristodera (extinct) |-- Trilophosaur idae (extinct) |-- Rhynchosaur idae (extinct) |-- Prolacertiformes (extinct) `-- Archosauriformes |-- Proterosuchidae (extinct) |? - Erythrosuchidae (extinct) |-- Euparkeriidae (extinct) `--+-- Proterochampsidae `-- Archosaur ia |-- Crurotarsi (including the Crocodiles) `-- Ornithodira |-- Pterosauromorpha (extinct) `-- Dinosauromorpha (including the Dinosaure S, which includes/understands the Oiseau X)
References
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