Protohoplites (Protohoplites) michelinianus  (d'Orbigny, 1841)

Measurements	D mm	H/D	T/D	O/D	H/T
CP-713	43	0.48	0.36	0.24	1.32
Lectotype	80	0.43	0.32	0.31	1.34

Age	Origin
Phosphatic nodules, condensed level S. kitchini to P.(H.) puzosianus zones Lower Albian	Machéroménil Ardennes France

Description. Reworked ammonite preserved in gray phosphate with remnants of a pearly test and a damaged venter at the beginning of last whorl. Whorls 60% covered, with a compressed trapezoidal section and slightly concave flanks converging towards a flat venter. Umbilicus with a 45° slope at the base and a long wall gently curving towards the flank. Elongated, pinched umbilical bullae, increasingly proverse, arise on the umbilical wall. They reach their maximum height slightly beyond the umbilical margin and sag on the inner third of the flanks. The ventrolateral shoulders bear prominent, rounded, irregularly spaced clavi, slightly inclined outwards, forming a 45° angle with the siphon. Each one is in line with its counterpart on the opposite side of the venter and connected to it by a weak bridge. Each umbilical bulla is connected to the two nearest clavi by two slightly sigmoid ribs. The front rib is roughly in line with the bulla, the rear rib is noticeably bent back. One of the two ribs, front or rear depending on the bulla of origin, is much weaker than the other and only visible in raking light. On the last half-whorl, there are 7 bullae, 8 clavi, and 12 ribs.

Remarks. An uncommon ammonite from the puzosianus zone of Southeast England (Folkestone) and the Ardennes in France (Macheroménil), illustrated by d'Orbigny (1841) and Casey (1965, pl. 81, fig. 1-2). The ribs disappear on the flanks at around 80 mm in diameter. In the most compressed forms, the ventrolateral tubercles are barely elongated and resemble outwardly inclined cones or horns. According to Matrion et al. (2000), this species could be a compressed form of Protohoplites (Protohoplites) archiacianus.