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 The Anatomy of Melancholy The Anatomy of Melancholy (full title: The Anatomy of Melancholy, What it is: With all the Kinds, Causes, Symptomes, Prognostickes, and Several Cures of it. In Three Maine Partitions with their several Sections, Members, and Subsections. Philosophically, Medicinally, Historically, Opened and Cut Up) is a book by Robert Burton, first published in 1621, but republished five more times over the next seventeen years with massive alterations and expansions. On its surface, the book is presented as a medical textbook in which Burton applies his vast and varied learning, in the scholastic manner, to the subject of