 The "Treatise on Invertebrate Paleontology" (Part L, 1957) divides the Ammonoidea, regarded simply as an order, into eight suborders, the Anarcestina, Clymeniina, Goniatitina, and Prolecanitina from the Paleozoic; the Ceratitina from the Triassic; and the Ammonitina, Lytoceratina, and Phylloceratina from the Jurassic and Cretaceous.In subsequent taxonomies, these are sometimes regarded as orders within the subclass Ammonoidea.Because ammonites and their close relatives are extinct, little is known about their way of life.