| Species | Atractites jeletzkyi MARIOTTI & PIGNATTI |
| Author | MARIOTTI PIGNATTI |
| Group | Atractiten |
| Horizon | naumanni-horizon |
| Zone | calliphyllum-zone |
| Stage | Lower Hettangian |
Description
The telum is quite large, spindle-shaped and slender. It becomes rapidly narrower adorally (towards the mouth) and is thin and cylindrical at the anterior end. The top view is symmetrical and spindle-shaped. In profile the telum is slightly asymmetrical, more convex on the ventral side than on the dorsal.
The apical angle is about 12°.
The cross-section of the telum is almost circular, only slightly compressed. At the proximal and distal ends it is circular.
A. jeletzkyi reaches its greatest thickness in the middle or even towards the front end.
The telum is apically (posteriorly) smooth, without sculptural elements. Irregular ring-shaped growth structures may be visible in front. The adoral end usually ends abruptly with a smooth break. One specimen is present where the transition to a phragmocone is preserved: the diameter slowly increases again and chambers are clearly visible. We assume that other phragmocomes with the same opening angle can also be placed with A. jeletzkyi.
Since the holotype is described from the Fonsjoch at the Achensee and specimens from the same locality from the same horizon are present here, these can be addressed as paratypes. Remarkable is the large diameter of some phragmocones that can be found. Assuming that they are the same species, one can conclude that the total length of telum + phragmocone is at least 50cm!
* Description according to Mariotti & Pignatti (1996), supplemented
Compare
Atractites alpinus is more oval in cross-section and reaches its greatest thickness closer to the posterior end or near the middle. The telum is generally thicker and the tapering at the apical (posterior) end is faster. In addition, the specimens are consistently taller.
The top view and profile of A. alpinus are clearly different from those of A. jeletzkyi.
Atractites alpinus also occurs later (in the upper Middle Hettangian), just below the marmoreum crust.
Remarkably, phragmocone remains are rarely found in the stratigraphic vicinity of A. jeletzkyi, which have a much larger angle and more closely successive chambers. Their systematic position is still unclear. Perhaps they are A. depressum HAUER as described by Mojsisovics.
Dimension
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Literature
- 1993 Atractites sp. 1 aff. A. alpinus Gümbel – Mariotti & Pignatti Taf. 1, 3-5
- 1996 Atractites jeletzkyi n.sp. – Mariotti & Pignatti, S. 211
