Rarities from the Northern Calcarious Alps: Hettangian Ammonites (Lias Alpha)

The triassic-jurassic boundary (200 Mill. years ago)

In former times (200 mill. years ago), the continents were pushed together to a giant supercontinent "Pangaea" and were surrounded by the "Panthalassa-sea." From the East, a huge bay, called Tethys reached into today's Mediterranean area to the northern edge of the Alps,. The Alps were folded later, so the fossil-sites are often at 1500 to 2000 m. The north-west of Europe - closer to the mainland was flooded only temporarily.

At the end of the Triassic Period (in the larger regression) takes place a big mass extinction. Ammonites were also affected. According to scientists, only Phyllocerataceae survived this time and formed the ancestors of the later Jurassic ammonites.

With the Hettangian begins the Jurassic period. While the lower Hettangian provides comparatively useful fossils (eg Psiloceraten) around the world , material from middle and upper Hettangian is rather poor. In the 19th Century there were at least well-preserved finds from the Salzkammergut. Obviously a major part of this material was destroyed or lost (2nd world war) or dormant in private collections.

The tenacity and resourcefulness Reinhard's, a fellow fossil-collector , is thanks to that I could specialize collecting in under-represented areas of the middle and upper Hettangium. Pursuing a vague reference we were looking for days, until finally in the "Saubach" he has found a negative of an ammonite and we could watch the film further. The hettangian Neoammonites shown here come the northeastern edge of the european alps nearby Salzburg (Salzkammergut) and were collected by me in the last 25 years. The digestion conditions are difficult, so I am afraid that further there will be not to much news. Historic fossil-sites, which are described, for example by Wähner (Rockfalls, in which each block has already been turned over or around small natural outcrops), were exploited a long time ago.

As far my treasures gather dust in the basement My treasures gather dust but probably as far from me in the collection. My homepage will change that and make it accessible to interested people. If there are any other collectors with this particular area of ​​interest, I would be grateful for an exchange of experiences.

If you can contribute to the completion of this review, I would appreciate hearing from you very much. I am open to consider corrections, suggestions and comments, please note, that I'm not a paleontologist.

Timor, at that time was apparently covered by the same ocean (Tethys). It belongs to the same faunal province with comparably good material.
Continental drift caused today's long distance.

Northwest Europe, however, was probably cut from the Tethys. The ammonite fauna of this area is significantly different in general, as the following overview shows.

Hettagium (Renevier 1864)

The International Stratigraphy Commission-(ICS),gave a span -200 to -196 million years (as of 2008).

The previous epoch, is named Rhaetium (Rhaetian)

the subsequent era known as Sinemurian.

Origin of the pieces: Northern calcarious Alps (Europe) - Lower Lias.

In my fossil-sites the Hettangian is deposited in condensation horizons.

The sediments of a million years, are sometimes only 10 to 15 cm thick. The material (including fossils) was often refurbished and rearranged. Therefore, only a sub-division into the three zones is possible. The most parts of the horizont are without any macrofossils. A fine stratigraphy (in subzones and horizons), as shown in a comparison between the situation NW-Europe, is usually not possible. Ammonites are frequently bad, or at least partially dissolved in a page. Curiously, there are some areas in which the layers are more powerful. Then, the Fossil density is reduced again, and in addition an accurate determination is more difficult because of the poor preservation.
Some areas of the Hettangium the Northern Limestone Alps are characterized by very low sedimentation rates. In the uppermost zone (marmoreum) there is formed a widespread ferromanganese crust. Increased flow activities, which had its origin in a global sea level depression might be the cause of the condensation.
The following survey shows the Zones, Subzones and Horizonts of the Hettangium in NW-Europe, for comparison, the alpine zones in brackets.

Subzones horizons NW Europe



Horizonts NW Europa

Schlotheima angulata
in the alps:


Schlotheima complanata

Schlotheima depressa

Schlotheima complanata

Schlotheima extranodosa

Schlotheima extranodosa

Alsatites liasicus
in the alps:

alpin: megastoma

Alsatites laqueus

Sunrisites hadroptychus

Alsatites liasicus

Alsatites laqueus

Waehneroceras portlocki

Waehneroceras portlocki

Psiloceras planorbis

in the alps:




Caloceras johnstoni

Caloceras belcheri

Caloceras johnstoni

Psiloceras planorbis

Psiloceras plicatulum

Psiloceras psilonotum

As mentioned, It is not possible for me to create a fine stratigraphy for my fossil-sites, as shown here for the NW-Europe relations, so I will confine myself to the mere enumeration of found genera and species, and leave this task to the professionals.

The Neo-Alpine Hettangian ammonites are represented by three families

• Phylloceratidae (Zittel 1884)
• Psiloceratidae (Hyatt 1867)
• Lytoceratidae ()

Beside these Families, the transition to the jurassic period was possible for:

• Orthoceratidae / Atractidiae (see Sonstige!)
• Nautiloidea (see Sonstige!)
• Gastropoda (see Sonstige!)

The images are already relatively large. Click on image to enlarge and see more details.

In my opinion, well preserved specimens like these, will be found only in this area and in Timor. For example, in northwest Europe most of these genera and species did not appear.

Enough of the introductory remarks. Be surprised by the diversity that nature has produced in this period:

If you are interested in more details about Ammonites and the Triassic-Jurassic boundary in particular, please look to my link-tips!

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