Abstract:
The most common continental stratigraphic units in the SW-German Miocene are the
the silvana-beds deposited prior to the Ries meteorite impact, as well as the post-
Ries deposited sylvestrina-beds (MN6-MN9). They contain a lot of different
landgastropods, which were studied with respect to taxonomy (including
morphometrics), palaeogeography and palaeoecology. The index fossils
Palaeotachea silvana and P. sylvestrina could be clearly separated with
morphometrical and statistical methods (Cluster analyses, PCA). Additionally, four
other Palaeotachea species could be identified in the studied SW German Miocene
deposits. At least 35 different species of landgastropods could be identified and
illustrated from the silvana-beds based on the deposits of Dischingen,
Hohenmemmingen and Mörsingen. The contemporaneous sediments of Randeck
Maar (MN5) provide insights into the gastropod diversity of an ancient Maar lake. All
in all 32 different continental gastropod taxa were identified from this locality. In the
younger sylvestrina-beds of the Steinheim Basin (MN7), 48 different landsnail
species could be described and illustrated. Taxonomic problems concerning the
Chondrinidae from the sylvestrina-beds were solved as well as the genus
membership of Pseudochlorits insignis. The majority of the landgastropods were
hydrophilic species and a lot of them have Recent relatives. However, the
sylvestrina-beds contain a higher proportion of xerophilic taxa. According to the
ecological preferences of the single taxa, different micro-habitats could be
reconstructed. During the research approximately 180 type specimens of continental
gastropods could be identified in the collection of the SMNS which were illustrated in
a type catalogue. Additional to the taxonomic work, statistical methods (Cluster and
NMDS analyses) were used to compare all published Middle Miocene continental
deposits in Middle Europe. The resulting clusters reflect the palaeogeographic
situation of that time interval. Finally, the taxonomic results were also used for a
species catalogue for the silvana-beds at the southern margin of the Swabian Alb.
silvana-beds