Family Girtyoceratidae Wedekind, 1918

Family diagnosis: Girtyocerataceae with ontogenetically changing conch shape; inner whorls evolute, umbilicus closing during ontogeny, adult stage often discoidal and oxyconic. Ornament with biconvex growth lines. Suture line with V-shaped external lobe and rounded ventrolateral saddle; adventive lobe V-shaped with slightly sinuous flanks.

Remark: For the genus composition of the family and a discussion of the characteristics and limits, see Korn and Titus (2011).