Ziegler, R.: Wirbeltiere aus dem Unter-Miozän des Lignit-Tagebaues Oberdorf (Weststeirisches Becken, Österreich) - 5. Marsupialia, Insectivora und Chiroptera (Mammalia). p. 43-97
Die Beuteltiere, Insektenfresser und Fledermäuse aus den Hangendschichten Oberdorf 3 und Oberdorf 4 der kohleführenden Abfolge des Kohletagebaus Oberdorf im Köflach-Voitsberger Kohlerevier, westlich von Graz, werden vorgestellt.
Die Beuteltiere sind durch ein post-agenisches Evolutionsniveau von Amphiperatherium frequens vertreten. Die meisten Fledermäuse können nur sehr grob oder nur mit Vorbehalt bis zum Artniveau bestimmt werden. Bei den Insektivoren fällt die Seltenheit (Oberdorf 3) beziehungsweise das gänzliche Fehlen (Oberdorf 4) von Igeln auf. Die Dimyliden machen in beiden Faunen über die Hälfte der Insektivoren aus. Die möglichen Ursachen der Faunenzusammensetzung werden diskutiert.
Die Insektivoren erlauben die Einstufung beider Faunen in das mittlere Orleanium, in die Säugerzone MN 4.
Schlüsselwörter: Mammalia, Didelphidae, Erinaceidae, Metacodontidae, Talpidae, Dimylidae, Soricidae, Vespertilionidae, Rhinolophidae, Molossidae, Biostratigraphie, Mittel-Orleanium, MN 4, quantitative Auswertung, Steiermark.
Summary
Vertebrates from the Early Miocene lignite deposits of the opencast mine Oberdorf (Western Styrian Basin, Austria). 5. Marsupialia, Insectivora and Chiroptera (Mammalia).
Oberdorf is situated in the Köflach-Voitsberg coal mining district, Western Styria Basin, in Styria, West of Graz. The fossil bearing layers Oberdorf 3 and Oberdorf 4 constitute the top of the coal bearing sequence of the Northern border of the Eastern depression. Oberdorf 3 is a thin coal layer with a basal concentration of bones, fruits and seeds, as well as some gastropods. Oberdorf 4 is a bipartitioned coal seam, some 12 cm on top of Oberdorf 3. On the bottom of the Oberdorf 4 seam there is also a concentration of vertebrates and gastropods. The small vertebrate faunas of Oberdorf are the most numerous hitherto found in Styria.
Here we summarize the biostratigraphic results, based on marsupials, insectivores and bats and present a concise quantitative analysis of these faunal elements.
Didelphidae – The marsupials of Oberdorf 3 and 4 are represented by a post-Agenian evolutionary stage of Amphiperatherium frequens, the only species in the Miocene of Central Europe. For both faunas a maximum age of MN 4 is indicated.
Erinaceidae – The fauna of Oberdorf 3 is certainly correlative with MN 4 by the cooccurrence of Galerix symeonidisi and Galerix aurelianensis.
Metacodontidae – Plesiosorex styriacus and Plesiosorex germanicus so far are scarcely documented in faunas correlative with MN 4 to MN 5. Because of uncertain discrimination of both species and in view of the poor documentation they are irrelevant for precise stratigraphy.
Talpidae – Desmanella engesseri hitherto is known only from Southern German faunas correlative with MN 4. The sample of Oberdorf 4, only determinable as D. aff. engesseri, does not allow precise biostratigraphic correlation.
Proscapanus aff. sansaniensis, documented by a single M2 in the Oberdorf 4 fauna, represents an intermediate stage betweeen Pr. intercedens and Pr. sansaniensis. Specimens like this occur in the time spanning MN 4 to MN 6.
The stratigraphic range of Talpa minuta, type locality Sansan (MN 6), is unknown. Similar forms still occur much earlier. Consequently T. minuta of Oberdorf 3 is an imprecise stratigraphic indicator.
According to its hitherto known occurrence Myxomygale hutchisoni indicates MN 4 as upper limit.
Desmanodon and the indeterminable talpid remains are of no use for biostratigraphy.
Dimylidae – Plesiodimylus aff. chantrei of Oberdorf 3 and Oberdorf 4 is more evolved than Pl. aff. chantrei of Petersbuch 2, thus indicating the upper half of MN 4 as maximum age. Chainodus intercedens of Oberdorf 4 is represented by an evolved sample and indicates a probable MN 4 age of the fauna.
Soricidae – The occurrence of Heterosorex neumayrianus aff. subsequens, an advanced evolutionary stage of the subspecies, also argues in favour of a MN 4 age.
Miosorex and Lartetium because of poor preservation and Florinia stehlini because of its long chronologic range are not usefull for stratigraphic correlation.
"Allosorex" gracilidens hitherto is only poorly known at Franzensbad (MN 5) and at Neudorf (type locality, MN 6). Considering the scarce documentation this species cannot validate a MN 5 or MN 6 age for the Oberdorf 3 fauna.
Chiroptera – Because of a taxonomic problem in recognizing Chiropteran lineages during this time interval we can not use bats effectively for biostratigraphic correlation.
In summary the insectivore species from Oberdorf 3 and 4 clearly indicate an MN 4 correlation (=middle Orleanian), which is supported by the rodent fauna.
Bats and didelphids only comprise 17% of the Oberdorf 3 non Rodent/Lagomorph small mammal fauna and 13% of the fauna of Oberdorf 4. The scarcity of the erinaceids, normally comprising 35 to 55% of the insectivore fauna of a site, is unusual. Obviously they are replaced by dimylids (mainly the less specialized Plesiodimylus), who constitute more than 50% of the insectivore fauna.
Keywords: Mammalia, Didelphidae, Erinaceidae, Metacodontidae, Talpidae, Dimylidae, Soricidae, Vespertilionidae, Rhinolophidae, Molossidae, biostratigraphy, Middle-Orleanian, MN 4, quantitative analysis, Styria.