The Ceratites of the
Muschelkalk of Lorraine


During the period of the Triassic, beginning the Mesozoic 250 million years ago, all of our today's continents were united in one large single surface - Pangea - translating as "the entire Earth", or "all the land". This supercontinent embraced an immense bay, the Tethys, a warm equatorial ocean whose tiny remains today make the Mediterranean Sea, the Black and Caspian Sea, as well as the Balaton Lake in Hungary. All other shores were borded by the "Panthalassa", the Great Ocean covering the entire rest of the planet, today`s successor being the Pacific Ocean.

During that time almost all of our today`s Central Europe was forming a depression covered by a warm and shallow sea close to the Tethys ocean - comparable in much bigger scale to the "Étangs", the shallow lagoons at the French Mediterranean coast. Shoals were reducing (and sometimes even preventing) water exchange between the Tethys and this Germanic Basin - its center being located in today's Central Germany. In fact, there were only two connections to the Tethys, the Silesian (or Moravian) Gate in the East, and the Burgundy Gate in the South-West. During this entire period our region was situated a few degrees North only off the Equator, where you will find today the southern rim of the Sahara desert.

These two gates were closing temporarily for a few million years, resulting an a complete desiccation of the basin with the deposition of mighty rock-salt layers, being exploited today in Germany (Bad Reichenhall, Bad Friedrichshall, Schwäbisch Hall) and in Lorraine (Dieuze, Marsal, Château-Salins).

The Muschelkalk (named like this because it first has been described scientifically in Germany, could be translated as "mussel-limestone" or "shelly limestone") occuring in vast areas of Central Europe did form out of the deposits in this basin. Divided by the period of repeted desiccations of the basin, Muschelkalk can be divided into three main sections:

The Lower Muschelkalk forming since the beginning of the flooding of the Germanic Basin 235 million years ago.
The Middle Muschelkalk with its rock-salt layers of the period of desiccations due to water supply cutoff from the Tethys.
The Upper Muschelkalk beginning with a new persistant flooding of the basin.

In the course of time the basin slowly filled up with debris from the erosion of the surrounding continent. Thus was ending, 220 million years ago, the period of the Muschelkalk with a change to more continental environmental conditions.

Due to its separated situation with reduced water exchange from the Tethys ocean, life conditions in the basin were all but comfortable: warm, oxygen-poor water, a hot tropical climate with heavy seasonal storms, a varying and often elevated salt concentration.... The ideal laboratory for evolution to give proof of the adaptive capabilities of life to hostile environments - by the development of endemic species, only existing there and especially being adapted to life under these conditions.

Among these, one of the most remarkable species are the Ceratites, a branch of the Ammonoidea endemic to the Germanic Basin. Invading through the Burgundy Gate at the beginning of the Upper Muschelkalk into a sea free of any concurrents, their tethydal ancestors quickly evolved into separated species perfectly adapted to the peculiar life conditions in the basin. Whilst their relatives in the oceans were preferring deeper seas, those adapted to life in shallow waters. For it is just in the bordering and coastal regions of the basin where they are most likely to be found today.

In the following time and especially towards the end, tiny species reaching hardly 10 cm in diameter developed into giant forms reaching easily over 30 - 40 cm across (the Discoceratites). Many things are still mysterious about them, and a puzzling number of species (over 40), subspecies and varieties has been described over the years. A magnificent and up-to-date documentation (in German) is given by the "Trias-Verein Thüringen", still located at the right place in the center of the Germanic Basin, in the state of Thuringia in Germany... ;-)

In our region these "Ceratite layers"of the Upper Muschelkalk appear in Eastern Lorraine, on both sides of the French-German border and in the area of the upper and central river Saar valley, as well as in the central and lower river Blies valley with its surroundings in the state of Saarland in Germany.

The following Ceratites can be found there, shown in the order of their evolution:

(click the photos for detailled information!)
1. Ceratites atavus
2. Ceratites pulcher

the earliest Ceratites,
no accessible layers
in our region
3. Ceratites robustus
4. Ceratites compressus

5. Ceratites evolutus
6. Ceratites muensteri
7. Ceratites spinosus

8. Ceratites posseckeri
9. Ceratites nodosus
10. Ceratites intermedius

11. Ceratites alticella
12. Discoceratites dorsoplanus
13. Discoceratites semipartitus
 

But Ceratites were not the only animals living in the Muschelkalk sea. They lived together with mussels, snails, crabs and lobsters, sea lilies (at certain periods and places), fish and - the first marine saurians! In the following a few examples:

Plagiostoma (Lima) striata
Pemphix sueri
Ceresiosaurus (vertebra)

Loxonema obsoleta
Encrinus liliiformis
Coenothyris vulgaris

All the fossils shown on this page: collection and property of Uli Siegel, Saarbrücken, except Encrinus liliiformis: collection of Geolor