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Micro Fossils |
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Calcareous nannofossils are fossil remains of golden-brown, single-celled algae that live only in the oceans. Because they are plants they need sunlight, so they float near the surface of the water. There are billions and billions of them living in the oceans today, and they are eaten by anything that is bigger than they are. They are one of the primary organisms at the base of the food chain. These algae make tiny calcite platelets inside their cells, and these platelets (the calcareous nannofossils or nannos for short) move to the surface of the cell. No one is certain why these platelets are formed, but after a while they fall off the cell and slowly drift down to the bottom of the ocean. These platelets are replaced by new ones that constantly are forming within each cell. As these platelets land on the bottom of the ocean, they are slowly covered up with remains of other plants and animals and bits of mud and sand that have washed out with the rivers of the world. At this point they are part of a mud or marl or sandy clay. Eventually, there are many sediments on the ocean bottom, and their weight is enough so that the lowest sediments are squeezed enough to become rocks. If these rocks are almost entirely made of nannos, they are a chalk. If there aren't so many nannos, they can be part of a limestone or shale. These calcite platelets are preserved in the rocks and are the fossils that paleontologists study. Calcareous nannofossils have been living in the
world's oceans for at least 210 MYA i.e. from the Late Triassic [Triassic
period: 248 - 208 MYA] and they have evolved and changed constantly over
time. |
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This collection is from different locations covered by a PhD research "Planktonic Biostrategraphy of Jordan, through the Cretaceous - Paleocene Succession", conducted by Smadi, 2000. Sixty-one species and sub-species of Plankton Foraminifera related to 21 genera and 50 calcareous Nannofossils species related to 25 genera. Nine biozones of calcareous Nannofossils were recognized in the study area. The studied geographical areas:
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