| Measurements | D mm | H/D | T/D | O/D | H/T |
|---|---|---|---|---|---|
| CP-428/74 | 49.5 | 0.43 | 0.49 | 0.31 | 0.87 |
| RJ-1245 figured | 56.7 | 0.47 | 0.49 | 0.25 | 0.96 |
| GSM 30946 Casey 1965 | 80 | 0.40 | 0.44 | 0.32 | 0.91 |
| BM C72831 Casey 1965 | 87(80) | 0.42 | 0.47 | 0.31 | 0.89 |
| Lectotype Douvillé 1911 | 87 | 0.44 | 0.48 | 0.28 | 0.92 |
| Age | Origin |
|---|---|
|
Mangystau: sinzowi zone, puzosianus subzone. France, England: puzosianus zone. Lower Albian |
North-Aktau Ridge Mangystau Peninsula Kazakhstan |
Description. A splendid specimen with whorls 40% covered and the body chamber on the last 120°. At the beginning of last whorl (35 mm), the slightly depressed hexagonal section is reminiscent of Sonneratia dutempleana. The deep umbilicus has a vertical wall as high as the flanks. The umbilical tubercles are not very prominent, and the arched, bifurcated ribs show a weak ventral sinus. They are only slightly proverse but already show a depression in the middle of venter. On the last half-whorl, the ribs become sharp and rise over the umbilical and ventral shoulders, forming triangular tubercles, which makes the venter and flanks slightly concave. They become more spaced out and cross the venter in a straight line, and a single tuberculate rib is inserted between the pairs. The rear rib of the pairs diverges increasingly from the anterior rib. The flanks become less convergent, which widens the venter. The ribs over the siphuncle become less depressed, but their height still appears reduced because the intercostal space remains slightly convex. The umbilical wall becomes less steeply inclined at the end of last whorl (45°). There are 13 tubercles and 21 ribs per whorl, 5 of which are isolated.
Remarks. Matrion in Colleté (2010) considers Hemisonneratia as a separate genus and therefore calls this ammonite Hemisonneratia puzosiana. This species is quite variable in the Anglo-Paris Basin, with pyritic or phosphatized specimens, most often fragmentary, and in Transcaspia, which has yielded complete and better-preserved specimens. The literature exaggerates the ventral collapse of the ribs, which is often subtle and/or late. This ammonite is unfortunately quite rare, which is unfortunate for a index fossil! In its absence, the puzosianus zone is characterized by the presence of Sonneratia dutempleana, Otohoplites raulinianus, Pseudosonneratia sp. and also, in Kazakhstan, of the genus Tetrahoplites.