before impact, thus transmitting the impact past the brain and allowing its whole body to help absorb the shock; its relatively small brain is less prone to concussion than other animals'. Some species have modified joints between bones in the skull and upper jaw, as well as muscles which contract to absorb the shock of the hammering. Strong neck and tail-feather muscles, and a chisel-like bill are other hammering adaptations which are seen in most species. Other species of woodpecker, such as the Flicker, uses its long tongue primarily to grab prey from the ground or from under loose bark. It has few shock-absorbing adaptations, and prefers to feed on the ground or to chip away at rotting wood and bark, habits observed in birds outside of the woodpecker family. A "continuum" in skull structures, from little- to highly specialized for pounding is seen in different genera (groups of related species) of woodpeckers alive today. In his classic "Birds of America," John James Audubon describes the slight gradations in hyoid horn length found in different species of living woodpeckers. The slack of tongue is kept under the loose skin behind its neck. The tiny bones divide into essentially two tongues, coming back together before entering the beak. Systematics The systematics of woodpeckers is quite convoluted. Based on an assumption of unrealistically low convergence in details of plumage and behavior, 5 subfamilies were distinguished. However, it has turned out that similar plumage patterns and modes of life are not reliable to determine higher phylogenetic relationships in woodpeckers, and thus only 3 subfamilies should be accepted. For example, the genera Dryocopus (Eurasia and Americas) and Campephilus (Americas) of large woodpeckers were believed to form a distinct group. However, they are quite unrelated and instead close, respectively, to the genera, Mulleripicus and Chrysocolaptes, of Southeast Asia. In addition, the genus allocation of many species, e.g. the rufous woodpecker, has turned out to be in error, and some taxa with unclear relationships could be placed into the phylogeny. In 1975 John Morony and colleagues in their Reference List of the Birds of the World divided the true woodpeckers into six tribes: Melanerpini, Campephilini, Colaptini, Campephilini, Picini, Meiglyptini. This classification was used in 1982 by Lesley Short in his Woodpeckers of the World. The introduction of molecular methods led to a substantial reorganization of the phylogeny making the earlier groups obsolete. In 2005 David Webb