Stem arteries of a crinoid
18,00 €
System: Ordovician.
Origin: Dalarna, Sweden.
Measurements: 10cm x 5cm
1 in stock
The fossils of Ordovician crinoids in Dalarna (Sweden was part of the Baltic continent, located in the southern hemisphere, near the equator) they are part of one of the tropical marine ecosystems most famous and studied of the Paleozoic.
During the Late Ordovician (about 450 million years ago), the Dalarna region, especially the area known as the Siljan Ring District, was submerged under a shallow tropical sea. In this environment, the first reef complexes in Europe developed where crinoids (sea lilies) were extraordinarily abundant. The characteristic landscape of this district was formed about 377 million years ago (during the Late Devonian period) when an asteroid about 5 kilometers in diameter impacted the Earth. The enormous collision generated an original crater estimated to be about 52 to 60 kilometers in diameter (the largest in Western Europe).
Over the millions of years that followed, erosion sculpted the terrain so that depressions in the outer ring filled with water, creating a circular system of interconnected lakes. The impact preserved and vertically exposed ancient Ordovician and Silurian marine sediments that would have otherwise been eroded.
