Rare starfish fossil discovered at Pfände: A treasure from the Miocene!

Rare starfish fossil discovered at Pfände: A treasure from the Miocene!

A remarkable fossil discovery has caused a stir on the Pfänden near Bregenz. A starfish whose remains are considered extremely rare has been discovered in the Upper Sea Molasse. Normally, starfish, which do not have a mineral skeleton, are difficult to find as fossils because their structures often break during the decomposition process. As the Small newspaper Reportedly, the starfish could be preserved through special deposition conditions. It is assumed that the animal sank into soft mud on the seabed at the time and was shortly afterwards covered by sand, possibly as a result of a storm.

The find is known as Asteriacites stelliformis and is located on the underside of a sandstone slab. Other fossils were also discovered during field studies in the Upper Molasse, including snails, oysters and scallops. A burrowing sea urchin found several years ago is also considered a rarity in this region. The remains of starfish are extremely rare in Vorarlberg, which makes this find particularly remarkable.

Geological backgrounds

The Molasse Basin in which this fossil discovery was made extends over approximately 800 km and was formed at the Eocene/Oligocene transition when the Pennine Ocean closed. This geological development resulted in the collision of the Adriatic and European plates, which led to the subsidence of the European continental plate. The deposits in this basin, known as “molasses”, are characterized by poorly consolidated sediments such as sands, silts and marls, as well as some conglomerates and limestones. The name “Molasse” is derived from French and means “soft,” which describes the nature of these sediments molasse-haie-rochen.de.

The filling of the Molasse Basin lasted from the Lower Oligocene to the Upper Miocene, over a period of about 25 million years. Sediment formation depended on various factors, including subsidence and orogeny. The main sediment supply came from the Alps, meaning that the sediments on the edge of the Alps had the greatest thicknesses of up to 5000 m.

Evolution of fossil diversity

The geological conditions in the Molasse Basin have contributed to the formation of a variety of fossils. The systematic division into different types of molasse is crucial for understanding the regional geology. This includes marine molasses, brackish water molasses and freshwater molasses and ranges from the lowest to the upper layers palaeontology.geosciences.uni-muenchen.de.

The lithostratigraphic division of the Molasse Basin includes a total of six groups, each of which provides further insights into the geological history and the development of the fossil fauna. The outcrop conditions on the north and south edges of the basin are particularly important for research. The starfish discovery is not only of scientific interest, but was also nominated as “Fossil of the Month” in the collectors’ magazine “Der Steinkern”, which underlines the importance of this historical find.