Related Directory Categories
- Birding (1880)
- Birds (1443)
- Species (1278)
- North America (1085)
- United States (834)
- Parrots (783)
- Birds (443)
- Europe (330)
- Birds (279)
- Pigeons (270)
Sources
Help build the largest human-edited directory on the web.
Submit a site - Become an editor
Wikipedia. Licensed under the GNU Free Documentation License.
Are you an expert in this subject? Join the discussion and share your knowledge at Wikipedia.org.
Keel (bird)
From Wikipedia, the free encyclopedia
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 ribs. The keel provides an anchor to which a bird's wing muscles attach, thereby providing adequate leverage for flight. Keels do not exist on all birds; in particular, some flightless birds lack a keel structure.
Historically, the presence or absence of a pronounced keel structure was used as a broad classification of birds into two classes: Carinatae (from carina, "keel"), having a pronounced keel; and Ratites (from ratis, "raft" — referring to the flatness of the sternum), having a subtle keel structure or lacking one entirely. However, this classification has fallen into disuse as evolutionary studies have shown that many flightless birds have evolved from flighted birds. The current definition of Carinatae now includes all extant birds.
- Cummins, Jim (April 1, 1996). "Anatomy of Flight". Retrieved January 31, 2005.
- Ramel, G. "The Anatomy of Birds". Earth-Life Web Productions. Retrieved January 31, 2005.