Late Viséan (late Mississippian) ammonoids from the Barnett Shale, Sierra Diablo Escarpment, Culberson County, Texas, USA Author Titus, A. L. D. Korn & Grand Staircase-Escalante National Monument, 669 S. Highway 89 A, Kanab, UT 84741, USA Author Korn, D. J. E. Harrell & Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstrasse 43, Author Harrell, J. E. L. L. Lambert & Noble Energy Inc., Houston, TX 77070, USA Author Lambert, L. L. Department of Geological Sciences, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA text Fossil Record 2015 2015-06-04 18 2 81 104 http://dx.doi.org/10.5194/fr-18-81-2015 journal article 298388 10.5194/fr-18-81-2015 49a593d2-44ce-420d-a608-8533ec6745ac 2193-0074 11585625

Table 6. Characteristics of genera within the subfamily Dombaritinae.

	Choctawites	Lusitanoceras	Revilloceras	Dombarites
General shape of inner	subevolute to evolute	subevolute	evolute	subinvolute
whorls
Whorl profile of inner whorls	whorls widest at some distance from umbilical margin, flanks diverging or subparallel, trapezoidal	whorls widest at umbilical margin, flanks converging	whorls widest at umbilical margin, flanks converging	variable
Constrictions	only on steinkern	on shell surface	on shell surface	often on shell surface
Coiling of inner whorls	rounded	usually triangular	triangular	triangular at some species
Ornament in the subadult stage	fine spiral lines	coarse spiral lines	coarse spiral lines	variable
Ornament in the adult stage	fine spiral lines, falcate transverse ornament	coarse spiral lines, occasionally falcate transverse ornament	coarse spiral lines, falcate transverse ornament	variable
Height of median saddle	0.60 of external lobe depth	0.50–0.55 of external lobe depth	0.50–0.55 of external lobe depth	0.65–0.75 of external lobe depth
Shape of external lobe	weakly Y-shaped	weakly Y-shaped	strongly Y-shaped	weakly Y-shaped
Width of external lobe	0.80 of E lobe depth	0.65 of E lobe depth	0.70 of E lobe depth	0.70–0.85 of E lobe
at half depth				depth
Shape of external lobe prongs	V-shaped	V-shaped	lanceolate	V-shaped or lanceolate
Flanks of adventive lobe	sinuous	slightly sinuous	with inflexion	with inflexion