| Measurements | D mm | H/D | T/D | O/D | H/T |
|---|---|---|---|---|---|
| CP-382/69 | 48.7 | 0.39 | 0.33 | 0.33 | 1.15 |
| 1014 Saveliev holotype | 58.7 | 0.44 | 0.34 | 0.24 | 1.29 |
| CP-372/53 | 55.5 | 0.43 | 0.34 | 0.26 | 1.26 |
| 1125 Saveliev | 71.6 | 0.40 | 0.32 | 0.28 | 1.25 |
| Age | Origin |
|---|---|
|
O. sinzowi zone, P. (H.) puzosianus subzone of the Mangystau Lower Albian |
North-Aktau Ridge Mangystau Peninsula Kazakhstan |
Description. Ammonite with whorls covered at 50% and the body chamber preserved on the last half-whorl. The section is compressed trapezoidal, with a venter which remains a little convex, rounded shoulders, and flat, slightly converging flanks, twice as wide as the venter. The umbilicus, a quarter of the diameter, has a wall at 70° which rounds towards the flank. 15 small umbilical bullae, protruding and projected forward, arise halfway up on this wall and give rise to pairs of sigmoid ribs crossing the venter with a proverse sinus at 130°. These bullae stretch over the last quarter of whorl. The 35 ribs have a steeper rear slope than the front on venter. They include here and there 9 intermediate ribs of variable length. The specimen complies with the description in Russian by Saveliev (1992).
Remarks. T. finitimus, only known in Mangystau, is often confused with Tetrahoplites rossicus (see its file), but the former has a smaller umbilicus, a higher and more curved umbilical wall, and lower ribs, with a greater number of intermediate ribs inserted here and there, which gives it a less regular ornamentation. The shape of the section evokes a Pseudosonneratia. For Saveliev (1992), it is a transitional form between this genus and Tetrahoplites (hence the name finitimus = intermediate). However, he places it in Tetrahoplites because it has persistent umbilical tubercles, a suture line identical to that of T. orientalis, ribs with an asymmetrical section. Moreover many samples present a filiform sulcus on the siphonal line, a typical detail of the genus according to him.