Hoplites (Hoplites) dentatus  (J. Sowerby, 1821)

Measurements	D mm	H/D	T/D	O/D	H/T
Jaffré 2007 p.75	60.5	0.48	0.37	0.23	1.27
RJ-43 figured	60.6 (52.7)	0.44	0.33	0.22	1.33
CP-626	65	0.42	0.32	0.28	1.32

Age	Origin
Dark-gray clay, bed C dentatus zone, Middle Albian	Dienville Aube, France

Var.	dentatus	spathi	paronai
H/T	1.21-1.32	0.92-1.02	0.67-0.83
T/D	0.32-0.40	0.49	0.52-0.70

Description. This pyritic internal mold is fully septate, with whorls of compressed trapezoidal section that overlap by 45%. The flanks are moderately convex, and the maximum whorl thickness is located at its lower quarter. The rather low umbilical wall, sloping at 45°, is flat and connected to the flank by a rounded edge. Nineteen radially pinched, slightly proverse umbilical tubercles give rise to pairs of fine but prominent ribs, regularly curved forward. The last half-whorl alternates between simple tuberculate ribs and shorter intercalary ribs. The slightly raised rib terminations meet the siphonal line at 45° and alternate on either side of it. They define a groove with a flared U-shaped section, with a straight, smooth band 2 mm wide at the bottom. Including a few simple ribs, there are 41 ribs at the top of the flanks.

Remarks. Personal discovery. Table 3 compares, by increasing thickness, the Hoplites with U-shaped sulcus from the base of the dentatus zone, on the specimens from Spath (1925). No clear boundary separates them. Today, they are considered variants of H. dentatus, which has anteriority (Amédro 1992; Courville & Lebrun, 2010; Amédro et al., 2014). The H/T ratio of 1.32 for CP-626 belongs to this form. The ammonite was found in the Aube riverbed, in a bed of pyritic phragmocones located 3.40 m above bed B. For a long time, authors have assigned all thick Hoplites to H. benettianus and the compressed ones to H. dentatus, regardless the ventral groove. It was Amédro (1992) who introduced the widening of the groove as a distinguishing criterion and who showed the lineage H. benettianus → H. dentatus.