The late Middle Miocene (late Sarmatian) flora of Graz-Andritz (Austria): Environmental, climatic, and biogeographic patterns

The Middle Miocene (late Sarmatian Central Paratethys stage) plant assemblage of Graz-Andritz comprises isolated leaves and a few fruit remains. The fossil-species represent mainly the swamp and riparian vegetation (cf. Glyptostrobus, Zingiberites, Platanus, Liquidambar, Ulmus, Myrica, Salix, Decodon, Byttneriophyllum / Banisteriaecarpum and others).

In addition, a number of plants probably grew at greater distance from the lake and represent well-drained lowland and upland forests. These include Buxus, Rosa, Fagus haidingeri, Betula similis, and Acer jurenakii. The flora of Andritz shows distinct similarities with Sarmatian and Pannonian plant assemblages in the Styrian and Pannonian basins (Gratkorn, Kirchberg / Raab, Paldau, Felsőtárkány, Rózsaszentmárton), sharing diagnostic taxa such as Zingiberites / Musophyllum, Acer jurenakii, Byttneriophyllum, and Banisteriaecarpum.

In addition, marked similarity is seen with Pontian / Dacian assemblages from the Transcarpathian Basin. Plant climate proxies from several Sarmatian localities in the Pannonian Basin indicate a climate with both temperature and precipitation seasonality but without severe drought periods. Biogeographic patterns in the leaf / fruit assemblage of Andritz show contrasting patterns of endemism and relictualism.

For instance, Acer jurenakii was an endemic element in the Pannonian Basin during the late Neogene. This pattern appears to be characteristic of temperate elements such as Berberis and Acer spp., which show a high degree of endemism during the Neogene of Central Europe. In contrast, Byttneriophyllum / Banisteriaecarpum was a fossil-taxon with a complex biogeographic history involving all of Eurasia and a stratigraphic range from the Eocene to the Pliocene.

This relict taxon in the Andritz flora went extinct during the Pliocene.