Bromacker

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Bromacker​
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Germany
View over one of the sandstone quarries at Bromacker

The quarries at Bromacker on the northern edge of the small town of Tambach-Dietharz in Thuringia are the most important find places for land vertebrates (Tetrapoda) from the Lower Permian period (approx. 298.9 to 272.3 mya ) outside of North America.

Geographical location

The Bromacker lies west of the L 1028 immediately north of Tambach-Dietharz. Therefore the fossil deposit located there is usually mentioned in connection with this small town. However, the quarries are located in the municipality of Georgenthal .

geology

Geological map of the Thuringian Forest . The Tambach basin is located on the northern edge of the Oberhofer Mulde in the central part of the Thuringian Forest.

The Bromacker is located in the Tambach Basin , a former rift valley in today's Thuringian Forest . The rocks there belong to the Tambach sandstone , which forms the middle part of the Tambach Formation . The Tambach formation belongs to the younger section of the Rotliegend series and is very likely Artinsky age (approx. 280 million years). The rock sequence on the Bromacker is divided into "lower layers" and "upper layers", which both consist of red sand , silt and clay stones , but differ slightly in terms of their characteristics. So all vertebrates found so far come exclusively from the "upper layers", predominantly from two approx. 0.5 meter thick banks , which consist of massive fine sand / siltstone and an approx. 0.5 meter thick, z. T. Conchostraken containing interval of flat fine sand / siltstone and laminated claystone are separated from each other. In relation to terrestrial vertebrates, the “lower layers” only contain trace fossils .

history

Live reconstruction of the “Tambach lovers”, two specimens of Seymouria sanjuanensis that were found in this position.
Two tetrapod stamps as a raised relief on the underside of the layer (positive hyporelief). The step seal in the right half of the picture belongs to the Ichniotherium trace genus . In addition to various other traces, the figure shows dry crack fillings .
The trace fossil Tambia spiralis attributed to an invertebrate as a positive hyporelief. A dry crack filling runs through the upper half of the figure.

The site was discovered in 1974 by the German paleontologist Thomas Martens . Since then, German and American paleontologists have been digging for fossils together in Bromacker . So far, in addition to a number of insect and plant fossils, over 40 skeletons of around 12 species of "primordial reptiles" have been brought to light. The current excavation area extends over 300 square meters, but test drilling has shown that a total of about 1–2 hectares could be searched for fossils.

Paleoecology and Finds

The sediments of the Bromackers were deposited in an outflow-free , mountain-lined plateau by small rivers and lakes. The climate at that time was very warm all year round with seasonal rainfall, i. H. there was a rain - and a dry season , similar to today's savannah . However, since there were no grasses in the Permian , the landscape hardly resembled the savannas of today. Rather, the flora was dominated by conifers and seed ferns .

The fish and amphibians typical of the fossil sites of the Lower Permian North America are missing in the Tambach Basin. Instead, only forms appear at the Bromacker which are largely adapted to a purely terrestrial way of life and which are largely herbivores. The reason for this could lie in the fact that the Tambach Basin was a deposit area which, in contrast to the fossil deposits in North America, was located far away from the coastal plains, and that these remote, isolated highlands in the Lower Permian were difficult to colonize by aquatic vertebrates . Therefore, food webs based on terrestrial herbivores formed there.

Vertebrate finds identified or described so far: Georgenthalia , an amphibamide ; Tambachia and Rotaryus , both trematopids ; two undescribed dissorophids ; Seymouria , the eponymous genus of Seymouriamorpha ; the Diadectomorphs Orobates and Diadectes ; the bolosaurid Eudibamus , capable of walking on its hind legs ; Thuringothyris , a representative of the " Protorothyrididae "; the large carnivorous pelycosaur Dimetrodon , the Varanopid Tambacarnifex and an undescribed Caseide .

The ostodolepid Lepospondyle Tambaroter described in 2011 from the Tambach Formation does not come from the quarries at Bromacker, but was found during construction work for a supermarket in Tambach-Dietharz. In addition, it probably does not come from the Tambach sandstone, but from the overlying Finsterbergen conglomerate .

So far identified or described trace fossils of terrestrial vertebrates: Ichniotherium , Varanopus , Tambachichnium , Dimetropus , Megatambichnus .

Invertebrate fossils identified or described so far at Bromacker : Lioestheria , a conchostrake ; the phyloblattid cockroaches cf. Anthracoblattina , Kunguroblattina and Phyloblatta ; the mylacrid cockroaches Moravamylacris and Opsiomylacris as well as several undescribed myriapods and insects.

So far , traces of invertebrates identified or described at Bromacker: Scoyenia , Tambia and Striatichnium .

literature

Individual evidence

  1. ↑ Marco Roscher & Jörg W. Schneider: An annotated correlation chart for continental Late Pennsylvanian and Permian basins and the marine scale . In: New Mexico Museum of Natural History and Science Bulletin . 30, 2005, pp. 282-291.
  2. ↑ a b c d Thomas Martens, David S. Berman, Amy C. Henrici & Stuart S. Sumida: The Bromacker Quarry - the Most Important Locality of Lower Permian Terrestrial Vertebrate Fossils Outside of North America . In: New Mexico Museum of Natural History and Science Bulletin . 30, 2005, pp. 214-215.
  3. ↑ Jason S. Anderson, Amy C. Henrici, Stuart S. Sumida, Thomas Martens & David S. Berman: Georgenthalia clavinasica , a new genus and species of dissorophoid temnospondyl from the Early Permian of Germany, and the relationships of the family Amphibamidae . In: Journal of Vertebrate Paleontology . 28, No. 1, 2008, pp. 61-75.
  4. ↑ David S. Berman, Amy C. Henrici, Thomas Martens, Stuart S. Sumida & Jason S. Anderson: Rotaryus gothae , a New Trematopid (Temnospondyli: Dissorophoidea) from the Lower Permian of Central Germany . In: Annals of Carnegie Museum . 80, No. 1, 2008, pp. 49-65. doi : 10.2992 / 007.080.0106 .
  5. ↑ David S. Berman, Amy C. Henrici, Stuart S. Sumida, Thomas Martens & Valerie Pelletier: First European Record of a Varanodontine (Synapsida: Varanopidae): Member of a Unique Early Permian Upland Paleoecosystem, Tambach Basin, Central Germany . In: Christian F. Kammerer, Kenneth D. Angielczyk & Jörg Fröbisch (Eds.): Early Evolutionary History of the Synapsida . Springer, 2014, ISBN 978-94-007-6840-6 , pp. 69-86.
  6. ↑ Amy C. Henrici, Thomas Martens, David S. Berman & Stuart S. Sumida: An Ostodolepid 'Microsaur' (Lepospondyli) from the Lower Permian Tambach Formation of Central Germany . In: Journal of Vertebrate Paleontology . 31, No. 5, 2011, pp. 997-1004. doi : 10.1080 / 02724634.2011.596601 .

Web links

Commons : Bromacker  - Collection of images, videos and audio files

Coordinates: 50 ° 48 ′ 35.2 ″  N , 10 ° 37 ′ 8.8 ″  E