| Measurements | D mm | H/D | T/D | O/D | H/T |
|---|---|---|---|---|---|
| CP-600 | 36 | 0.50 | 0.35 | 0.06 | 1.52 |
| David Joly | 65 | 0.57 | 0.38 | 0.06 | 1.48 |
| Age | Origin |
|---|---|
|
Lower Albian D. inaequinodum Malagasy zone |
Malandiandro outlier Boeny Region Madagascar |
| Comparative ratios | T/D | H/T |
|---|---|---|
| For eight P. (H.) velledae | 0.36 – 0.42 | 1.39 – 1.72 |
| For five P. (G.) inflatum | 0.46 – 0.54 | 1.15 – 1.27 |
Description. A fully septate specimen, thick and involute, with slightly convex flanks, thickest at the inner third. Compressed elliptical whorl section with a broad, rounded venter. Ornamented with 213 closely spaced, sigmoid riblets, indistinct at the base of the flanks. They originate proversely at the umbilicus, follow a convex arc up to 40% of the flank height, then an almost straight, slightly retroverse course, and finally a less curved concave section near the venter. They cross the venter, forming a weak, proverse, and rounded sinus. Some are grouped in bundles: a primary riblet can successively branch into secondary riblets. The test is nearly complete. Where missing, riblets are still visible on the internal mold, and portions of phylloid sutures can be observed.
Remarks. This species existed from the Late Aptian to the Middle Cenomanian and has been found in France, Bulgaria, Crimea, Sardinia, the Balearic Islands, and Madagascar (Joly, 1998; Kennedy & Klinger, 1977). Even without a visible suture, it is easily recognizable in the Albian, where it is the only Phylloceras with this compressed cross-section, slightly convex flanks, and rib shape. It is rare in the Paris Basin, but beautiful specimens reaching 20 cm have been found in the benettianus zone of the Aube Albian, notably at Epothémont and Courcelles. Almost all Malagasy Phylloceras specimens found on the Internet fossil markets are labeled Phylloceras velledae, but more than 90% are actually Goretophylloceras inflatum (see its entry). This one can be identified by its thicker whorl section (see the 3rd table above, from Prins, 2005), and its less incised suture line. Thanks to David Joly for lending us his specimen!