Microfossils
- Created by: Brad_ers_B
- Created on: 18-04-15 12:27
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- Microfossils
- Ostracods
- Have two valves, hinge with teeth and sockets + adductor muscles (Like bivalves)
- Less than 2mm in length
- The Shell/ carapace made of chitin or calcium carbonate
- Cambrian - Present Day (earliest groups extinct)
- Mainly Benthonic mode of life so limits use in dating rock
- Good palaeo-environment indicators with different forms in waters with different salinity
- Foraminifera
- Mostly single-celled creatures with a protective shell/test
- Range from 1 µm to around 110 mm
- Modern foraminifera capture food using thread-like structures
- Most forms are benthonic (sessile or vagrant) but some planktonic
- Early Cambrian - Present day (Planktonic forms uncommon until Mesozoic)
- Excellent stratigraphic tool in oil industry, also provides evidence on evolution changes
- Conodonts
- Range from 200 µm to 5 mm and are the teeth of a soft-bodied creature
- Teeth are composed of calcium phosphate, apatite, occur in pairs and known as conodont elements
- First found in Precambrian rocks - Died out in Permo-Triassic extinction event
- Radiolaria
- Marine+Planktonic animals, range from 30 µm to 2 mm
- Composed of silica, occupied niches from surface to hundreds of metres in depth
- Rich diversity of delicate silica skeletons so are preserved at depths below the CCD and easy to recover
- Been around since Precambrian and excellent stratigraphic and palaeo-environment tools
- Spores and Pollen
- Composed of sporopollenin
- Between 10 and 200 microns in diameter
- Spores found in Ordovician, earliest plants producing pollen were Late Devonian
- Pollen diversified in the Cretaceous
- Lived on either land or marginal shallow water so can easily be washed out to sea
- Ostracods
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