| Species | Caloceras avus Kment |
| Author | KMENT |
| Group | Psiloceraten |
| Horizon | costosum-horizon |
| Zone | calliphyllum-zone |
| Stage | Lower Hettangian |
Description
The body is evolute and has an almost round winding cross-section on the innermost windings. The umbilical edge is rounded and the umbilical slope is steep. The innermost two to three coils are smooth, no nodule stage is present. Thereafter, slender and low ribs gradually develop, starting at the coiling suture, crossing the flank in a backward sloping arc and then rapidly weakening on the outer third of the flank. As they do so, they bend forward and split into several accretion strips that cross the external side. The ribs are highest on the middle of the flank.
The prairie line is quite simple and symmetrical.
* Description according to Kment (2021), supplemented
Compare
The absence of the nodule stage is unambiguous for the genus Caloceras. However, the preservation is often too poor to be able to judge this. Then the small specimens are often indistinguishable from similarly old Psiloceras like Psiloceras calliphyllum, Psiloceras strongolum, Psiloceras costosum.
Widely forked Waehneroceras waehneri are very similar, especially in the ribbing, but the nodule stage is present, although more or less distinctly developed.
Caloceras avus is probably very closely related to Psiloceras or Waehneroceras.
Dimension
Dimensions with D= 26mm
Nw % v. D: 42%
Wh % v. D: 33%
Wb % v. D: 25%
Literature
- 1952 Psiloceras (Caloceras) torus (DʼORBIGNY). – LANGE, p. 102, pl. 13, fig. 17.
- 2021 Caloceras avus n. sp. – KMENT, S. 250, Abb. 8.7-8.9, 13.2
