Keel (bird anatomy) 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. 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
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