| Measurements | D mm | H/D | T/D | O/D | H/T |
|---|---|---|---|---|---|
| CP-155 figured | 66.4 (55.5) | 0.42 | 0.53 | 0.31 | 0.79 |
| RJ-691 | 74.6 | 0.40 | 0.48 | 0.31 | 0.83 |
| Jaffré 2007 p.85 | 95 | 0.42 | 0.52 | 0.27 | 0.81 |
| Age | Origin |
|---|---|
|
Phosphatic nodules Top of dentatus zone Middle Albian |
Courcelles quarry Clérey, Aube France |
Description. Phragmocone in black phosphate followed by the body chamber in gray limestone on the last half-whorl, with one face missing. The whorls, hexagonal in section, overlap by 60%, with a tendency to uncoil over the body chamber. Umbilicus fairly wide and deep, connected to the flank by a rounded edge. Eleven slightly proverse primary ribs originate on the umbilical wall. They rise into strong triangular tubercles, initially located on the umbilical edge and then moving to mid-flank on the body chamber. Two very prominent secondary ribs project forward from each tubercle. The posterior rib of the pairs often diverges from the anterior rib, before folding forward. The terminations of secondary ribs reach a 60° angle to the siphonal line and rise sharply to form spatulae. They alternate on either side of the siphon, defining a wide, deep groove with a flared U-shaped cross-section. Compared to specimen RJ-691, this ammonite is slightly thicker and more spiny.