Micropaleontology: Includes study of microscopic remains of prokaryotes and eukaryotes, representing tiniest (bacteria) to largest (trees) of organims.

Good record of some fossil protists (single-celled eukaryotes):

Acritarchs:

• Range 1.7 Ga to... Devonian? Permian? Hard to say
• Probably not a monophyletic group
• Organic walled cysts of… something
• Spheroids with various degrees of ornamentation

Chitinozoa:

• Range Ordovician to earliest Mississippian
• Possibly eggs of graptolites and/or conodonts
• Organic walled chambers with “neck”, often arranged in chains

Dinoflagellates:

• Range Silurian onward; continuous record from mid-Triassic of dinocysts
• Organic walled
• Several different components to life cycle
• Normal preservation is of “dinocysts” (inactive stages), including hystrichospheres

Coccolithophorids:

• Range Late Triassic onward, peaking in Cretaceous
• Calcareous plates (coccoliths) arranged into coccospheres
• Life cycle not well studied

Foraminiferida:

• Range earliest Cambrian onward
• Multichambered
• Basal forms are agglutinated, later calcareous (becoming common in Devonian)
• Alternation of generations
• Particular groups of paleontological importance:
  • Fusulinina: Pennsylvannian-Permian, up to 10 cm long
  • Globogeriina: Middle Jurassic onward, very common from Cretaceous onward, planktonic
  • Nummulitidae: mid-Eocene, extremely large

Diatoms:

• Range possibly in Jurassi; definitely late Early Cretaceous onward (Paleogene for Pennales)
• Single chambered
• Silicaceous frustules
• Complex alternation of generations
• Two major groups:
  • Centrales: primitive, probably paraphyletic, radial symmetry
  • Pennales: derived, likely monophyletic, bisymmetrical

Radiolaria:

• Range possible latest Proterozoic, definitely by Silurian
• Single or multichambered
• Siliceous tests
• Probably have alternation of generations (not well studied)

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