Miocene Continental Gastropods from the Southern Margin of the Swabian Alb (Baden-Württemberg, SW Germany)
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N. Jb. Geol. Paläont. Abh. 287/1 (2018), 17–44 Article E Stuttgart, January 2018 Miocene continental gastropods from the southern margin of the Swabian Alb (Baden-Württemberg, SW Germany) Olaf Höltke, Rodrigo B. Salvador, and Michael W. Rasser With 6 figures Abstract: The Middle Miocene silvana-beds outcropping at the southern margin of the Swabian Alb bear a wide array of terrestrial and freshwater gastropods. Especially in the surroundings of the Emerberg and Tautschbuch hills, there are records of several collection sites. In the present work, we investigated material from the historical localities from these two regions, housed in museum collec- tions, in order to provide an updated check list, synthesizing the knowledge of the region in the hopes to spur renewed interest. In total, we report 14 freshwater and 50 land snail species from the area, but not all species reported in the literature could be confirmed. Key words: Baden-Württemberg, European Land Mammal Zone MN 5, Langhian, silvana- beds, Upper Freshwater Molasse. 1. Introduction (1923-1930). Therefore, in the absence of more driven excavations for the moment, here we investigated ma- The southern margin of the Swabian Alb, especially terial from several historical localities from these two the Emerberg and Tautschbuch hills, bears a consider- regions, housed in museum collections. Our goal is to able number of continental Miocene deposits (Fig. 1). provide an updated check list of species and localities, These are built up by the silvana-beds, a lithostrati- thus synthesizing the knowledge of the region in the graphic unit of the Miocene Upper Freshwater Molasse hopes to spur renewed interest and collection efforts. (“Obere Süßwassermolasse” or OSM), which is a unit of the North Alpine Foreland Basin. The silvana-beds are famous for the occurrence of large quantities of 2. Geological background fossil gastropods, both terrestrial and freshwater. In the works of the famous pioneer geologists of the 19th The southern margin of the Swabian Alb region is lo- century, like QUENSTEDT and FRAAS, localities from this cated within the North Alpine Foreland Basin (also area (e.g., Zwiefalten-Mörsingen) were always featured named “Molasse Basin”), which was formed during the in the section on the Tertiary of SW Germany. uplift of the Alps. For a detailed overview of the North Despite the rich occurrence of often well-preserved Alpine Foreland Basin and its evolution, see RASSER & fossil shells, there has never been a systematical palae- HARZHAUSER (2008) as well as GEYER & GWINNER (2011) ontological excavation in this region. The finds listed in and the references therein. the literature, as well as the material stored in museum The outcrops in the regions studied in this paper collections, are all “accidental finds” and, for many lo- are located within the OSM and, more specifically, be- calities, the most recent publication is the work of WENZ long to the unit known as silvana-beds, named after the ©2018 E. Schweizerbart’sche Verlagsbuchhandlung, Stuttgart, Germany www.schweizerbart.de DOI: 10.1127/njgpa/2018/0704 0077-7749/2018/0704 $ 7.00 eschweizerbart_xxx 18 Olaf Höltke et al. Fig. 1. Map showing the localities treated in this work. most commonly found fossil land snail: Palaeotachea served. HAAG (1960) also mentioned marls and clays silvana (KLEIN, 1853). For a stratigraphic overview see with a more or less distinct proportion of sand. Fig. 2. The underlying strata of the silvana-beds in the SChwARZ (1913) divided the silvana-beds from the region discussed herein are older Tertiary sediments Tautschbuch/Emerberg region in three different parts, see (Fig. 2) or the silvana-beds were deposit directly on mainly based on the lithology. The lowest part consists Upper Jurassic limestones (SChwARZ 1913). According of a brown plant and pisolithic limestone (“Pflanzen- to ESU (1999), the silvana-beds are dated from the Eu- und pisolithische Kalke”); the middle part is a light ropean Land Mammal Zone MN 5, which ranges from coloured limestone and a multicoloured marl; and the ca. 15.8 to 13.8 myr (BERGER et al. 2005). upper part a light coloured hard limestone (for more Unfortunately, outcrops in the Emerberg and details, see SChwARZ 1913). Apart from molluscs, there Tautschbuch hills are rare today, hence information are hardly any other fossils known from the silvana- about their lithology come either from the literature beds of this region; there are records only of a few plant or are based on observation of the few exposed out- remains (Celtis sp.) and ostracods from Zwiefalten- crops (in this decade, Zwiefalten-Gauingen, Zwiefalten- Mörsingen (as stated above, SChwARZ 1913 named the Zwiefalten-Mörsingen and Riedlingen) and loose rocks. lowest stratum as “plant limestone”, but gave no further Different lithofacies have been observed, ranging from details on plant fossils). The situation concerning non- hard and splintery freshwater limestone, to marls with mollusc fossils, however, might only be so because the different proportions of chalk and clay, to softer clays sediments have never been thoroughly examined. Like- in which the continental molluscs are often well pre- wise, more specific details on these regions’ geology is eschweizerbart_xxx Miocene continental gastropods from the southern margin of the Swabian Alb 19 Fig. 2. Stratigraphic overview of the study area (modified after SChwEIGERT 1996 and GEYER & GWINNER 2011). scarce. Only three localities from this region have been several species are known from other areas. The classifica- studied in more depth so far: Zwiefaltendorf (SCHLIC- tion used here follows mainly BOUCHET & ROCROI (2005) and NORDSIECK (2014). KUM 1976) and Riedlingen-Bechingen and Riedlingen- Daugendorf (SALVADOR & RASSER 2016a), with a paper on Zwiefalten-Mörsingen being in preparation (HÖLTKE & RASSER, in prep.). 4. Checklist of taxa Neritimorpha 3. Material and methods Family Neritidae In search of OSM fossil continental molluscs from the Emer- Theodoxus crenulatus (KLEIN, 1853) berg and Tautschbuch regions, most major museum col- Fig. 3.1 lections in Germany, Switzerland, Austria and the United Kingdom were contacted, as well as several local collec- Illustrated in: KLEIN (1853, pl. 5, fig. 18); SANDBERGER (1875, tions in Baden-Württemberg state. However, only a few of pl. 28, fig. 13); HARZHAUSER et al. (2012, fig. 2); SALVADOR et them housed specimens from the studied region, namely: al. (2016a, pl. 3, figs. 6-7). the following collections were examined: Bayerische Staats- sammlung für Paläontologie und Geologie (BSPG; Munich, Verified distribution: Altheim near Ehingen (Donau), Germany); Department of Geosciences, Eberhard Karls Uni- Zwiefalten (type locality), Zwiefaltendorf. versität Tübingen (formerly Geologisch-Paläontologisches Institut Tübingen, GPIT; Tübingen, Germany); Natural His- Further literature data: Riedlingen-Pflummern (WENZ tory Museum (NHMUK; London, UK); Paläontologisches 1928: 2945). Institut und Museum der Universität Zürich (PIMUZ; Zurich, Switzerland); Staatliches Museum für Naturkunde Stuttgart (SMNS; Stuttgart, Germany). In addition, the record of two Caenogastropoda species from the Gauingen locality stem from the private collection of DIETRICH KADOLSKY (Sanderstead, UK). Family Melanopsidae The gastropod species recorded are listed below (bi- Melanopsis kleinii (KURR, 1856) valves are represented only by undeterminable valve frag- Fig. 3.2 ments), with information on their occurrence in the Emer- berg and Tautschbuch regions that could be confirmed with Illustrated in: SCHLICKUM (1976, pl. 5, fig. 65); ESU (1980, fossil material. When the type locality of some species is fig. 8). located in the region discussed herein this is marked after the locality name. The material examined (with inventory num- Verified distribution: Altheim near Ehingen (Donau), Hau- bers) is fully listed in the Appendix. Additional occurrence sen ob Allmendingen, Zwiefalten-Mörsingen, Zwiefalten, data gathered from the literature are presented separately. Zwiefaltendorf. Please note that the “Verified distribution” and “Further lit- erature data” topics in the check list below refer only to the Further literature data: Deutschhof near Riedlingen- Emerberg and Tautschbuch regions, which are the focus here; Pflummern (WENZ, 1923: 2766). eschweizerbart_xxx 20 Olaf Höltke et al. Fig. 3. eschweizerbart_xxx Miocene continental gastropods from the southern margin of the Swabian Alb 21 Family Pachychilidae Further literature data: Emerberg near Zwiefalten, Tinnyea lauraea (MATHÉRON, 1842) Deutschhof, Langenenslingen-Friedingen (WENZ 1923: 1821). Fig. 3.3 Illustrated in: MATHÉRON (1842, pl. 36, figs. 23, 24); PAPP Pomatias consobrinus (SANDBERGER, 1875) (1953, pl. 3, fig. 29); SCHLICKUM (1976, pl. 1, fig. 9); Mikuž & Fig. 3.5 Pavšič (2000, pl. 1, figs. 1-8); SALVADOR et al. (2015b, fig. 2A, B); SALVADOR & RASSER (2016a, fig. 2); SALVADOR & RASSER Illustrated in: SANDBERGER (1875, pl. 29, fig. 33A); FRAAS (2016b, fig. 2A, B); SALVADOR et al. (2016a, pl. 4, fig. 19, pl. (1910, pl. 67, fig. 5); SCHLICKUM (1976, pl. 1, fig. 1); KÓKAY 9, fig. 17); SALVADOR et al. (2016b, fig. 4c-d). (2006, pl. 4, fig. 3); SALVADOR (2014, figs. 1, 2). Verified distribution: Langenenslingen-Andelfingen, Verified distribution: Ehingen (Donau), Zwiefalten-Mör- Riedlingen-Bechingen (cf.), Ehingen (Donau)-Dächingen singen, Zwiefaltendorf. (cf.), Ehingen (Donau), Zwiefalten-Mörsingen, Zwiefalten, Zwiefaltendorf. Further literature data: Emerberg near Zwiefalten, Hausen