| Measurements | D mm | H/D | T/D | O/D | H/T |
|---|---|---|---|---|---|
| CP-381/68 | 50.5 | 0.48 | 0.35 | 0.26 | 1.40 |
| Sinzow pl.2 fig.20-21 | 73.0 | 0.46 | 0.32 | 0.21 | 1.48 |
| Age | Origin |
|---|---|
|
vnigri zone, caperata sz and sinzowi zone, puzosianus sz in Mangystau. floridum and puzosianus zones in England and France. Lower Albian |
North-Aktau Ridge Mangystau Peninsula Kazakhstan |
Description. An involute and highly compressed ammonite with whorls that overlap by 60%. The body chamber occupies the last half-whorl. The whorl section is ogival, with an arched venter lacking distinct ventrolateral shoulders. The maximum thickness is reached at the inner third of the flanks. Fifteen very elongated umbilical bullae give rise to pairs of flexuous, prominent, thin, and closely spaced ribs, with some bundles of three or four. Along with twelve shorter intermediate ribs, there are a total of 42 similar ribs on the venter, which they traverse, forming a strong sinus with a fold close to 90°.
Remarks. This species was reported in Machéromesnil (Ardennes) by Breistroffer (1947) and in Mangystau. Along with Sonneratia (Eosonneratia) titovi Saveliev, it is the only Sonneratia species with a very compressed oval whorl section and a narrow rounded venter. The Auxerre Museum holds a "Hoplites (Sonneratia) quercifolius" from the 1850s, originating from Raveuse, Yonne, which is in fact a typical S. (E.) tenuis (Ricordeau collection no. 2017.0-64). S. (E.) titovi is a closely related species with far fewer (9-10) and very elongated umbilical tubercles. It displays the same number of ribs, but they are more flexuous and include more simple ribs (19-22). S. (E.) caperata has the same proportions as the present species, but with a slightly flattened venter, blunt ribs, a slightly more closed umbilicus, and a slightly lower T/D ratio. See our entries for these two species. Finally, thanks to Laurent Zimmer (Lithologia) who translated Sinzow's description from German for me!