This form of wine vessel only existed from the Anyang period of the Shang dynasty to the middle Western Zhou dynasty. The shape of the vessel helped to pour the wine and the cover sealed-in warmth and kept out contaminants. These vessels are called zoomorphic (shaped as an animal), and usually had the head of a tiger or a dragon forming the front of the cover. The cover on this bronze has the head of a bottle-horn dragon with sharp serrated teeth, the body ending in a coiled tail.
Ritual wine vessel and cover, gong Shang dynasty (about 1500-1050 BC), about 1100-1200 BC © Compton Verney