| Carinatae Fossil range: Cretaceous - Recent |
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In phylogenetic taxonomy, the Carinatae are considered the last common ancestor of Neornithes (living birds) and Ichthyornis (an extinct seabird of the Cretaceous). The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of Ichthyornis is a Genus of Seabird from the Late Cretaceous of North America. Chordates ( Phylum Chordata) are a group of Animals that includes the Vertebrates together with several closely related Invertebrates Birds ( class Aves) are bipedal endothermic ( Warm-blooded) Vertebrate animals that lay eggs. Ornithurae (meaning "bird tails" in Greek) is the name of a natural group of Birds coined by Ernst Haeckel in 1866 A clade is a taxonomic group comprising a single Common ancestor and all the descendants of that ancestor Ichthyornis is a Genus of Seabird from the Late Cretaceous of North America. Modern birds (subclass Neornithes) are the members of class Aves that have survived into recent times and have coexisted with Humans Modern birds are Modern birds (subclass Neornithes) are the members of class Aves that have survived into recent times and have coexisted with Humans Modern birds are Birds ( class Aves) are bipedal endothermic ( Warm-blooded) Vertebrate animals that lay eggs. Ichthyornis is a Genus of Seabird from the Late Cretaceous of North America. The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of Defined in this way, the group includes all living birds, including ratites (ostrich, emu, etc. Birds ( class Aves) are bipedal endothermic ( Warm-blooded) Vertebrate animals that lay eggs. A ratite is any of a diverse group of large Flightless birds of Gondwanan origin most of them now extinct The Ostrich ( Struthio camelus) is a large Flightless bird native to Africa (and formerly the Middle East) The Emu ( Dromaius novaehollandiae, is the largest Bird native to Australia and the only extant member of the Genus ), as well as neognathous birds and a few Mesozoic forms. The Mesozoic Era is one of three geologic eras of the Phanerozoic eon.
History
Traditionally, Carinatae were defined as all birds having a keeled sternum. A keel in Bird anatomy is an extension of the Sternum which runs axially along the midline of the sternum and extends outward perpendicular to the plane of the The sternum (from Greek στέρνον sternon, "chest" or breastbone) is a long flat Bone located in the center of the thorax (chest The carina or "keel" referred to a strong median ridge running down the length of the sternum, or breast bone. This is an important area for the attachment of flight muscles. Thus, all flying birds have a pronounced carina. Ratites, all of whom are flightless, lack a strong carina. Thus, living birds were divided into carinates and ratites. They also have a pterygoid bone that articulates with the palatine by means of a joint. The vomer is reduced or absent. [1]
The difficulty with this scheme was that there have been (and still are) any number of flightless birds, without strong carinae, but which are descended directly from ordinary flying birds with carinae. Examples include the turkey, a galliform (chicken-like) bird, and the dodo, a columbiform (the pigeon family). A turkey is either of two extant Species of large Birds in the Genus Meleagris native to North America. The dodo ( Raphus cucullatus) was a Flightless bird endemic to the Indian Ocean island of Mauritius. None of these birds are ratites. Thus, this supposedly distinctive feature was easy to use, but had nothing to do with actual phylogenic relationship. The use of this term to describe the Ichthyornis-Neornithine group turned out to be equally inapt. Various dinosaurs -- apparently, remote ancestors and cousins of the Carinatae -- do possess a keeled sternum. So, evidently the presence of this structure does not necessarily imply its use in flight. Flight is the process by which an object achieves sustained movement either through the Air (or movement beyond Earth's atmosphere, in the case of This sort of definitional problem is one reason why the use of physical characteristics to name taxonomic groups is now discouraged. The characteristics that actually are unique to the Carinatae have little to do with the sternum. Rather, carinates are unique in having, for example, a globe-shaped, convex head on the humerus and fully fused bones in the lower leg and outer arm. The humerus is a Long bone in the Arm or Forelimb that runs from the Shoulder to the Elbow.
References
- ^ W. R. Ogilvie-Grant (1921) Guide to the gallery of birds. Part 1. British Museum. (2nd Edn)
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