| Measurements | D mm | H/D | T/D | O/D | H/T |
|---|---|---|---|---|---|
| 1316 Saveliev | 40.5 | 0.44 | 0.33 | 0.23 | 1.33 |
| CP-416/155 | 48.1 | 0.41 | 0.34 | 0.30 | 1.21 |
| 1307 Saveliev holotype | 59.0 | 0.42 | 0.33 | 0.26 | 1.27 |
| Age | Origin |
|---|---|
|
O. sinzowi zone, P. (H.) puzosianus subzone of the Mangystau Lower Albian |
North-Aktau Ridge Mangystau Peninsula Kazakhstan |
Description. A flat ammonite preserved as a brown internal mold, with the body chamber preserved on the last third of last whorl. Only the suture of the last septum is discernible, but it is poorly exposed. The whorls overlap by 50%, but only by one-third at the end of the spiral, due to a vertical contraction of the body chamber. The whorl section is moderately compressed, with a high trapezoidal, almost rectangular, shape. The umbilicus has a flat wall sloping at 45°, which rounds towards the flanks. Each of the 13 prominent, elongated umbilical bullae give rise to two bifurcated, sharp ribs, sigmoid at the beginning of the last whorl and then almost straight. They reach their maximum height on the ventrolateral shoulders, where their posterior slope rises, then cross the venter, forming a broad, rounded sinus and sagging above the siphon. This sagging only becomes apparent at 28 mm in diameter, at the first third of last whorl. On the last half-whorl, some ribs are no longer clearly connected to their umbilical bulla. Furthermore, a single tuberculate rib is inserted between the last pairs of bifurcated ribs. There are a total of 21 ribs of similar appearance on venter.
Remarks. This species was named without a diagnosis by Saveliev in 1974 (nomen nudum) and then described correctly in 1992. It belongs to a group of Protohoplites defined by this author: P. hemilevis, P. solaris, P. transitorius, and P. subtransitorius. These rather similar forms from Mangystau, perhaps conspecific, are more compressed than the Protohoplites (Hemisonneratia) puzosianus of the Anglo-Paris Basin. Protohoplites (Hemisonneratia) solaris is distinguished within its group by its slightly flexuous, almost straight ribs. This appearance results from the radial or slightly proverse umbilical tubercles. The ammonite thus resembles a small sun, hence its name solaris.