Girtyoceratidae Wedekind, 1918

Titus, A. L., Korn, D., Harrell, J. E. & Lambert, L. L., 2015, Late Viséan (late Mississippian) ammonoids from the Barnett Shale, Sierra Diablo Escarpment, Culberson County, Texas, USA, Fossil Record 18 (2), pp. 81-104 : 86

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).