Girtyoceras 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 : 87

Girtyoceras Wedekind, 1918

Type species: Adelphoceras meslerianum Girty, 1909 (original designation).

Genus diagnosis: Girtyoceratidae with moderately large conch that during ontogeny passes through very different morphological stages: early juveniles are widely umbilicate with crescent-shaped whorl cross section, later thickly discoidal or pachyconic with subangular or rounded umbilical margin. The intermediate stage has rounded flanks and venter and the adult stage is lenticular and oxyconic. Without or with very faint ventrolateral grooves. Suture line with Vshaped external lobe, moderately high median saddle, narrowly rounded ventrolateral saddle, and V-shaped adventive lobe.

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