Keel (bird anatomy) Keel (bird anatomy) A keel or carina (plural carinae) in bird anatomy is an extension of the sternum (breastbone) 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 orders: Carinatae (from "carina", "keel"), having a pronounced
The Anatomy of Melancholy and others – make it a valuable contribution to multiple research disciplines. Burton was an obsessive rewriter of his work and published five revised and expanded editions of "The Anatomy of Melancholy" during his lifetime. It has often been out of print, most notably between 1676 and 1800. Because no original manuscript of the "Anatomy" has survived, later reprints have drawn more or less faithfully from the editions published during Burton's life. Early editions are now in the public domain, with several available in their entirety from a number of online sources such as Project Gutenberg. In recent years, increased