Urasterella asperula
Geological Time: Lower Devonian, Seigenian - Emsian Stage
Size (25.4mm=1 inch): Fossil has 55 mm armspan (if outstretched) on a 160 by 140 mm matrix
Fossil Site: Hunsruck Slate, Bundenbach Germany
Code: RS11
Price: $295.00 - sold
 Description:
Well-preserved example of an Ophuroid (brittlestars) known as Urasterella
asperula. The Hunsruck slate is famous for its fossils, many of which
have pyritization present. Rapid burial and pyritization was what
led to the many wonderful examples of early Devonian life from the
region. The chemistry of the silt was such that low organic content
and high levels of iron and sulfur allowed the pyrite to diffuse into
the tissues rather than be deposited in the sediment. The mudstones
were metamorphosed into slate during the Carboniferous. The slate
was quarried for roofing tiles, and the quarrymen would save the fossils
for later sale. Now that the quarries are no longer open, future supplies
of these wonderfully-preserved benthic organisms will only come from
existing collections. This one is in apical view. There is a missing
tip to one arm, which may have been lost antemortem. Another is shorter
than the others, showing it was in the process of regeneration when
the starfish died. The orientation of the arms is a result of a slow
current which was flowing from top right to lower left in the last
2 photos. |
