Microfossils

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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

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