The Middle Miocene freshwater mollusk fauna of Lake Gacko (SE Bosnia and Herzegovina): taxonomic revision and paleoenvironmental analysis

Abstract

The early Middle Miocene Lake Gacko was part of the Dinaride Lake System (DLS) and gave rise to a poorly known freshwater mollusk fauna. This was subject to malacological studies from the late 19th century onwards. Herein, we provide the first thorough taxonomic survey of Lake Gacko including revisions of several taxa. A total amount of 1,077 specimens was obtained from 17 samples, comprising at least 11 freshwater and 2 terrestrial gastropod species and 6 bivalve species. So far, none of the described taxa has been documented outside the Dinarides and the DLS, respectively. The fauna shows variable overlap with other paleolakes of the DLS, proofing once more the complex biogeographic patchwork of this system. The current paleoenvironmental reconstructions are tested and refined by application of a statistical analysis. This confirms the partition of the sedimentary history of Lake Gacko into three major depositional phases responding to astronomically forced climate changes. The low diverse mollusk assemblage in the initial phase, with abundant pulmonate and rissooid gastropods, signals a more arid climate with lowered lake level. During the second interval, the fauna becomes more diverse with common rissooid and melanopsid gastropods. It represents a more humid interval with enhanced precipitation and increased lake level, entailing the installation of a perennial lacustrine environment. The final phase is a return to arid conditions with the same elements as in the initial pulmonate‐rissooid assemblage. The sphaeriid Pisidium vukovici n. sp. is introduced as new species. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The freshwater mollusk fauna of the Middle Miocene Lake Drniš (Dinaride Lake System, Croatia): a taxonomic and systematic revision

“…Apparently this seems to be particularly true for Fossarulus species. Neubauer et al (2013b) already synonymized the three taxa endemic for the Gacko Basin with F. moniliferus Brusina, 1876 from Ribarić (Sinj Basin), showing that the single taxa actually represent ecophenotypes (see also Mandic et al, 2011). There, sculpture ranged from weak traces of keels to prominent ridges with nodules.…”

“…Likewise, the mention from Frankfurt-Praunheim (Praunheim Formation, middle-late Burdigalian) by Fischer and Wenz (1925) is very doubtful. Distribution: Sinj Basin (Ruduša, Trnovača, Turjaci, Župića potok), Drniš Basin (Biočić, Miočić, Parčić), Gacko Basin (Gračanica, Vrbica) (Brusina, 1884;Neubauer et al, 2013b). Records from the Early/Middle Miocene of the Knin Basin (Golubić) and the Pliocene of Nona (= Nin) listed by Wenz (1928) together with the one from the Late Miocene of Livno Basin (Čelebić-Jaruga, Šaćirovina) by Jurišić-Polšak and Slišković (1988) …”

“…The record of F. bulici from the Late Miocene Pannonian Basin by Papp (1953) is doubtful and needs a more detailed re-evaluation. Distribution: Drniš Basin (Vrba), Sinj Basin (Ribarić), Gacko Basin (Gacko, Gračanica, Vrbica), Kupres Basin (Kupres) (Brusina, 1876(Brusina, , 1884(Brusina, , 1897Krstić et al, 2013;Neubauer et al, 2013b); its occurrence in the Pliocene of Kočevje (Protzen, 1932) needs verification. (Neumayr, 1869;Brusina, 1874Brusina, , 1897Kerner, 1906;Jurišić-Polšak, 1984;Jurišić-Polšak et al, 2000).…”

Early Miocene gastropod and ectothermic vertebrate remains from the Lesvos Petrified Forest (Greece)

“…4h resembles G. pulici (Brusina, 1897) from the early Middle Miocene of the Gacko Basin (Neubauer et al 2013b) in terms of size and the position and expression of the angulation. Differences are the wider coiling and the unsymmetrical shape of the aperture of G. pulici.…”

“…Emmericia and Bania are particularly diverse and likely originate in the Dinaride Lake System (e.g. Neubauer et al 2013aNeubauer et al , 2013b.…”