Where: Hesse, Germany (49.9° N, 8.8° E: paleocoordinates 47.3° N, 4.6° E)

• coordinate stated in text

• hand sample-level geographic resolution

When: Middle Eocene (47.8 - 37.7 Ma)

• Palynozone PZ4, with Plicatopollis spp. and T. cingulum as dominant elements at the top of the zone.

•The pollen and spore taxa are also known from the nearby lacustrine record of Messel (see Thiele-Pfeiffer 1988), which is of latest early Eocene to early middle Eocene age (Lenz et al. 2015). It can be assumed that the lacustrine sequence at Groß-Zimmern is of a similar age. Accordingly, the palynomorph assemblage fits best to zones Hu4 to Ho2 of Pflug (1986) and 14 to 15 of Krutzsch (1966), which correspond to a middle Eocene (Lutetian/Bartonian) age.

•Punctilongisulcites microechinatus occuring in this sample is restricted to the middle Eocene.

Environment/lithology: crater lake; shale

Size class: microfossils

Preservation: original sporopollenin

Collection methods: core, chemical, mechanical, hydrochloric, hydroflouric

• Samples were crushed into small fragments and homogenised. A standard sample size of 4 g was used to minimise variations of reaction parameters such as sample surface area (Ellin and McLean 1994). Together with the sample material, 10 ml of 45% hydrofluoric acid (HF) were filled into a digestion vessel. Six vessels were used at the same time for digestion in the microwave system. The sealed vessels were treated by a standardised process with 15 minutes of heating at 110 °C using 1000-watt power and 45 minutes of cooling. Afterwards, the residue was mixed with 0.5 g of boric acid (H3BO3) to neutralise excess HF thereby improving safety for sample handling (Wilson et al. 2006). The residue in the vessels was then heated again for 5 minutes to 160° C by applying a power of 1000 watt. Following another cooling period of 45 minutes, the residues could be transferred into larger containers, which were filled with demineralised water and regularly decanted until neutralisation. After sieving through a 10 μm mesh screen, the residues were briefly oxidised by applying hydrogen peroxide (H2O2). Subsequently, the residues were sieved again, mixed with 5% potassium hydroxide (KOH) solution, and heated to 80 °C for 10 minutes in the MARS VI system. At the end of sample processing, the remaining residue was provided with a small amount of 35% hydrochloric acid (HCl) to solve remaining fluorides. After final sieving, the residues were transferred into crimp-top vials

•and 2 drops of 35% HCl were added to provide a slightly acidic environment that prevents fungal infestation.

•Slides and residues are housed at the Senckenberg Research Institute and Natural History Museum, Frankfurt am Main, Germany.

Primary reference: J. Mutzl, O. K. Lenz, V. Wilde, K. J. Krahn, M. Moshayedi and M. Hinderer. 2023. Vegetation dynamics in a disturbed lacustrine record: The Eocene maar lake of Groß-Zimmern (Hesse, Germany). Palaeobiodiversity and Palaeoenvironments 103:249-276 [P. Jardine/H. Morck]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 235239: authorized by Phillip Jardine, entered by Hannah Morck on 14.06.2024

Creative Commons license: CC BY (attribution)