Sprecher
Beschreibung
Seagrasses are marine plants forming dense underwater meadows, which are among the most productive and valuable ecosystems on Earth. They have a long evolutionary history, descending from flowering land plants that returned into the ocean over 75 million years ago. The almost exclusively marine sediments of the Münsterland Cretaceous Basin occasionally yield plant fossils – mainly leaves from trees of the forests thriving near the coast, which were washed or blown into the sea. However, there are also fossils of angiosperms that were embedded in situ – seagrass-like plants of the order Alismatales – the only group of flowering plants with a submerged lifestyle in marine environments. Thalassocharis westfalica is the most common species of these found in late Campanian strata of Westphalia. It was first described in 1880 by the Münster-based palaeontology professor August Hosius and pharmacist/botanist Wilhelm von der Marck from Hamm, and is now serving as logo of this conference. A few isolated finds of Posidonia cretacea are also known from the area. The fossils show that a rich seagrass community already existed in the coastal waters of Westphalia and the surrounding area during the late Campanian and Maastrichtian. Given that the world’s oldest known seagrasses date from the early Campanian, the presence of well-developed seagrass communities in the late Campanian of Westphalia reflects a remarkably short period for establishing such highly diverse ecosystems. It also unveils rapid adaptive evolution of the plants as they had to quickly adapt to a saline and thus primarily hostile environment.