Introduction Flashcards
Name the major microfossil groups:
- Prokaryotes (cyanobacteria in PreCambrian);
- Protistants (acritarchs, radiolarians, foraminifera;
- Plants (spores and pollen);
- Animals (ostracods, conodonts, SSF)
How long does the microfossil record extend to?
Archean (3.5Ga) - Eubacteria, cyanobacteria
How can microfossils be characterised, give examples?
By their skeleton composition:
- calcareous (ostracods, foraminifera, nannoplankton)
- siliceous (diatoms, radiolarians)
- phosphatic (conodonts, SSFs)
- organics (chitinozoans, acritarchs, dinoflagellates, SCF)
What are the environmental ranges of microfossil groups:
- use diagram*
- Pollen and spores from land to marine
- ostacods and diatoms in freshwater and marine
- acritarchs and benthic foraminifera in marine shelf and basin
- chitinozoans, nannoplankton, planktonic foraminifera, radiolarians in marine basin
State the geological history of microfauna
Hadean: Prebiotic world Archean: 3.8Ga origin of life Proterozoic: 2.5Ga Earliest cyanobacteria 1.8Ga Early eukaryotes (acritarchs) BORING BILLION L. Proterozoic: SSF E.Cambrian: Forams L.Cam.: Possible Ostracods, conodonts Mid. Ord.: Ostracods, Spores L.Dev.: Gymnosperm Pollen Triassic: Dinoflagellates, nannoplankton Jurassic: Diatoms, Angiosperm pollen
Why are microfossils important?
- Identifying the early evolution on earth, only fossil for about 3Ga
- Help explain some important feedback loops between early evolution of the planet and biosphere
Whats the other name for organic walled microfauna?
palynomorphs
name the organic walled microfauna:
- Acritarchs
- Chitinozoans
- Dinoflagellates
- Pollen and spores (terrestrial)
What was the range for dinoflagellates and what forms do they come in?
Cambrian?
- Triassic to recent
Photosynthetic and heterotrophic forms, it is the cyst that preserves as a fossil
- expelled from coral in dying reefs
Name the microfossils that contribute to the silica cycle
- Diatoms
- Radiolarians
- Silicoflagellates
When do the silica based microfauna range?
- Radiolarians: Cam - recent, marine photic zone to abyssal depths
- Diatoms: Lower Jurassic - recent, Marine and freshwater
- Silicoflagellates: Lower Cret. - recent, marine photic zone
How many species of diatoms are there?
100,000, responsible for circa 45% of primary production in the ocean - organics
Which microfauna are important for the carbon cycle and palaeoclimate?
- Ostracods
- Foraminifera
- Nannoplankton
When do the calcareous microfauna range?
- Ostracods: Ordovician - recent, abyssal planes to damp leaf litter
- Foraminifera: Lower Cambrian - recent, freshwater to deep ocean
- Nannoplankton: Triassic - recent, marine photic zone
How many living species of ostracod are there?
65,000, most abundant arthropods in the fossil record, reflective of ecology
How many species of foram are there?
38,151 fossil and 8981 living, providing the best record of deep time climate
What microfauna are responsible for 45% of marine primary productivity?
Algae: Coccolithophores (calcareous nannoplankton) and diatoms (siliceous)
