Tissotiidae is a family of ammonites (Ammonitina) belonging to the Acanthocerataceae. The Tissotiidae are derived from the Vascoceratidae, another acanthoceratacean family, and gave rise to the Coilopoceratidae. They have been divided into two subfamilies, the earlier and more primitive Pseudotissotiinae and the more advanced and later Tissotiinae, which differ only in the details of the suture. (ibid)