Einschluss einer männlichen Eichenblüte (Quercus emanuelii) in Bitterfelder Bernstein, Untermiozän, ca. 23 Millionen Jahre alt. Foto: Eva-Maria Sadowski/Museum für Naturkunde Berlin
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If you are lucky, you will find amber on a beach stroll along the Baltic Sea. The fossilized resin lumps are washed up with onshore wind especially after stormy winter days.

For her award-winning doctoral thesis, a researcher from the Museum für Naturkunde Berlin investigated plant inclusions in amber and reconstructed past Baltic forests. She continues her work on the amber collection of the museum and expands the research area in a new project.

Past Ecosystems

“The goal is to examine plant inclusions in amber, to identify them and to draw conclusions about their ecosystems,” said palaeobotanist Eva-Maria Sadowski. Some of the plant parts enclosed in resin flows millions of years ago – usually leaves, flowers or seeds of less than one centimetre in size – are well preserved in shape and even on cellular level.

“We can use these objects to understand distribution patterns and morphological evolution of plant families,” said Sadowski. Further questions concern the resin itself. With Baltic amber, for example, it is unclear which plant produced so much resin and which factors caused mass resin production.

The first step in the investigations is to find useable specimens for study. “I am very fortunate to be able to work with pre-sorted collections, including some from private collectors,” said Sadowski.
With Baltic amber, only about one in a thousand pieces has an inclusion. Only two to three out of a hundred inclusions are plant material. Of these, only a small fraction is suitable for in-depth research.

For her doctoral thesis, Sadowski investigated amber mainly from the Baltic Sea region. In a project approved by the German Research Foundation, Sadowski will supervise a doctoral student to investigate amber inclusions from Myanmar and China. The specimens originate from the Middle Cretaceous about 98 million years ago, the Early Eocene about 50 to 53 million years ago and the Middle Miocene about 15 million years ago. The recently discovered finds from both countries have so far been little examined for traces of past plant communities. Insights could contribute to the understanding of the rapid spread and diversification of flowering plants in the Cretaceous period.

Promising revisions

Some of the amber specimens are grinded and polished to optimize the visual investigation of the inclusion. Next, the amber inclusions are examined and photographed using a light microscope. In some cases, small samples are extracted from the inclusions for electron microscopic examinations. The palaeobotanist also applies micro-computed tomography at the Museum and the Deutsches Elektronen-Synchrotron (DESY, Hamburg) to reveal internal structures of the plant inclusions. An amber laboratory for further preparations is currently being set up at the museum.

The Museum für Naturkunde Berlin preserves one of the largest and most valuable collections of Baltic and Bitterfeld amber in Europe. Many of the finds have only been examined once so far and some of the related publications are more than one hundred years old. They are often scientifically outdated, but are still being cited. “Revising these first descriptions by applying new technologies and the current state of knowledge is very promising,” said Sadowski.

Sadowski received the Wolfgang Strutz PhD award for her dissertation “Towards a new picture of the 'Baltic Amber Forest' - Flora, habitat types and palaeoecology” at the University of Göttingen. The Senckenberg Society for Nature Research honours outstanding dissertations in the fields of biology, palaeontology or geology.

Related Publications

  • Sadowski et al. 2019. How diverse were ferns in the Baltic amber forest? Journal of Systematics and Evolution, doi: 10.1111/jse.12501
  • Sadowski, E.-M., Hammel, J.U., Denk, T. (2018) Synchrotron X-ray imaging of a dichasium cupule of Castanopsis from Eocene Baltic amber. American Journal of Botany, 105 (12): 2025-2036. doi:10.1002/ajb2.1202
  • Sadowski, E.-M., Schmidt, A.R., Seyfullah, l.J., Kunzmann, L. (2017). Conifers of the ‘Baltic amber forest’ and their palaeoecological significance. Stapfa, 106: 1-73. ISSN 0252-192X

Project-titel

Reconstructing fossil-rich East Asian amber forests using inclusions of seed plants

Funding

Deutsche Forschungsgemeinschaft – DFG