evolution and classifications
Evolution and classification
Main article: Evolution of birds
Archaeopteryx lithographica is often considered the oldest known bird
The first classification of birds was developed by Francis Willughby and John Ray in their 1676 volume Ornithologiae.[5] Carolus Linnaeusmodified that work in 1758 to devise the taxonomic classification system currently in use.[6] Birds are categorised as the biological classAves in Linnaean taxonomy. Phylogenetic taxonomy places Aves in the dinosaur clade Theropoda.[7]
Definition
Aves and a sister group, the clade Crocodilia, contain the only living representatives of the reptile clade Archosauria. During the late 1990s, Aves was most commonly defined phylogenetically as all descendants of the most recent common ancestor of modern birds andArchaeopteryx lithographica.[8] However, an earlier definition proposed by Jacques Gauthier gained wide currency in the 21st century, and is used by many scientists including adherents of the Phylocode system. Gauthier defined Aves to include only the modern bird groups, thecrown group. This was done by excluding most groups known only from fossils, and assigning them, instead, to the Avialae,[9] in part to avoid the uncertainties about the placement of Archaeopteryx in relation to animals traditionally thought of as theropod dinosaurs.
Gauthier[10] identified four conflicting ways of defining the term "Aves", which is a problem because the same biological name is being used four different ways. Gauthier proposed a solution, number 4 below, which is to reserve the term Aves only for the crown group, the last common ancestor of all living birds and all of its descendants. He assigned other names to the other groups.
Crocodiles
Birds
Turtles
Lizards (including Snakes)
The birds' phylogenetic relationships to major living reptile groups.
1. Aves can mean those advanced archosaurs with feathers (alternately Avifilopluma)
2. Aves can mean those
Main article: Evolution of birds
Archaeopteryx lithographica is often considered the oldest known bird
The first classification of birds was developed by Francis Willughby and John Ray in their 1676 volume Ornithologiae.[5] Carolus Linnaeusmodified that work in 1758 to devise the taxonomic classification system currently in use.[6] Birds are categorised as the biological classAves in Linnaean taxonomy. Phylogenetic taxonomy places Aves in the dinosaur clade Theropoda.[7]
Definition
Aves and a sister group, the clade Crocodilia, contain the only living representatives of the reptile clade Archosauria. During the late 1990s, Aves was most commonly defined phylogenetically as all descendants of the most recent common ancestor of modern birds andArchaeopteryx lithographica.[8] However, an earlier definition proposed by Jacques Gauthier gained wide currency in the 21st century, and is used by many scientists including adherents of the Phylocode system. Gauthier defined Aves to include only the modern bird groups, thecrown group. This was done by excluding most groups known only from fossils, and assigning them, instead, to the Avialae,[9] in part to avoid the uncertainties about the placement of Archaeopteryx in relation to animals traditionally thought of as theropod dinosaurs.
Gauthier[10] identified four conflicting ways of defining the term "Aves", which is a problem because the same biological name is being used four different ways. Gauthier proposed a solution, number 4 below, which is to reserve the term Aves only for the crown group, the last common ancestor of all living birds and all of its descendants. He assigned other names to the other groups.
Crocodiles
Birds
Turtles
Lizards (including Snakes)
The birds' phylogenetic relationships to major living reptile groups.
1. Aves can mean those advanced archosaurs with feathers (alternately Avifilopluma)
2. Aves can mean those