Soom slate
 
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The Soom Shale , often in the literature Soom Shale called, is one of the few Konservatlagerstätten the Ordovician . The deposit is located in the Western Cape Province of South Africa. The deposit is unique in that it is located at 32 ° south latitude, but was created in a cool, glacial, marine environment. In 1967 brachiopods and trilobites became known here, which were the first among Paleozoic fauna to be described from South Africa. However, the Soom slate is famous for its exceptional conservation of conodonts .
Discovery story
In the landscape of the western Cape region, which consists mainly of sandstone slopes and plateaus, the Soom slate layer has been noticeable for a long time. However, it was assumed that the layer was as low in fossils as these sandstones. Trace fossils were first discovered in 1958. In 1983 conodonts with soft tissue were also found here. These fossils were mostly known from small, phosphatic rows of teeth. Since the Conodonten Promissum pulchrum also had cartilage-supported eyes, it was clarified that this group belonged to the early fish. In 1995, conodonts with muscle tissue were even found here. Notable finds from the Soom schist also include details of the musculature and intestines of the Eurypterid Onychopterella .
Features of the Soom slate
The Soom slate reaches a maximum thickness of 10 meters and is finely banded from yellow-brown to light and dark gray. In an up to 130 meters thick DISA is siltstone -Subformation. Together they form the Cedarberg formation. The main site is near Keurbos Farm, about 13 kilometers south of Clanwilliam .
No trace fossils are found in the Soom slate. Presumably, the animals could not exist in the sediment and directly on the sea floor. From the shape of the fossil record, it was concluded that the water was cold, shallow, or at least not too deep, and showed no significant current. The soil waters were believed to be anoxic , meaning they did not contain oxygen or were toxic in some form. However, there were many swimming creatures in the water column above. In addition to the Euryptids and Conodonts, the cephalopods (cephalopods) to be found there were probably scavengers and / or predators. The brachiopods and cornulitides were among the filter feeders .
supporting documents
literature
- Paul Selden , John Nudds: Window on Evolution - Famous Fossil Findings of the World (translated by Jens Seeling), Elsevier Spectrum Academic Publishing House, Munich 2007, ISBN 978-3-8274-1771-8