Microfossils

Diverse "group" of small organisms or parts of organisms.

Chapter 11- Prothero - Micorpaleontology: Fossl Protistans (also mention of some other groups)

Some "important" ones:

Kingdom Monera:

Cyanobacteria (Archean-Holocene): prokaryotes, commonly form stromatolites; marine, freshwater, hypersaline water. (No lab specimens, but let's talk about this).

Kingdom Protista (a paraphyletic kingdom):

Amoeboid eukaryotes having pseudopodia. Grouped as either AUTOTROPHS or HETEROTROPHS.

Heterotrophs (Zooplankton):
     Phylum Sarcomatigophora

Subphylum Sarcodina: Radiolaria, Foraminifera.

Class Granuloreticulosa

     Subclass Rhizopoda (amoebas with thin pseudopods

     known as rhizopods)

Order Foraminiferida (C-Holo): calcareous or agglutinated tests, various spiral shapes; benthic since the Cambrian, planktonic since the Mesozoic, marine; form Globigerina oozes. Larger foraminiferida include fusulinids (Pl-Pm; shaped like rice grains) and nummulitids (Tertiary; coin-shaped).

Several suborders of forams

Chitinous: (not usually preserved)

Agglutinated: make tests from sand grains, other tests, etc.

Calcium Carbonate:

Hyaline: translucent/transparent, usually perforated to capture food w/protoplasm. Porcelaneous: opaque, usually nonperforared.

Subclass Radiolaria (Cambrian-Holo): siliceous tests, commonly spiny; planktonic, marine; contribute to siliceous oozes. 100 to 2000mm (2mm).

Order Spumellaria: spherical; spicules tend to have rounded edges; dominate shelf/slope.

Nassellaria: not sperical, usually conical (may be bilateral); spicules tend to have jagged edges; dominate open ocean.

Autotrophs (Phytoplankton):

Division (=Phylum) Chrysophyta (golden-brown algae) (Jurassic-Holocene):

Class Bacillariophyceae: diatoms; bivalved shells (frustules), opaline silica frustrule that is either centric or pennate; photosynthetic; planktonic and benthic, marine and freshwater; major primary food source; contribute to diatomaceous (siliceous) oozes. <1 to 2000mm (2mm)

Phylum(Division) Chrysophyta (Late K-Holo):

Class Coccolithophyceae (coccolithophorids) (Tr-Holo): disks made of radially arranged calcite plates; photosynthetic; contribute to calcareous oozes; photic zone (to about 50 m); narrow temperature range (warm water, largely restricted to 45°N to 45°S), marine; major primary food source; suffered mass extinction at the end of the Cretaceous but underwent adaptive radiation in the Paleocene. Motlite stage with 2 flagella and haptonema. <60mm. Nannofossils.

Silicoflagellates: marine, flagellate, photosyntheic planktonic protists, secrete opaline silica test (ring-like, hexagonal, or hemispherical lattice). Temperature sensitive and good indicators of temperature fluctuation. 20 to 100mm.

The microfossil groups below: not discussed in lab, but let's talk briefly about these. We will cover ostracods when we talk about the Arthropoda. Maybe we will look at some conodonts later.

Kingdom Plantae:

Phylum Chlorophyta (Proterozoic-Holocene): calcareous (aragonitic) and noncalcareous green algae; photic zone, warm water, marine and freshwater; disks of calcareous species are major contributors to carbonate mud. Charophytes (D-Holo) produce rounded, spirally coiled oogonia (female sex organs); freshwater, perhaps marine in the Devonian.
Dinoflagellata (Proterozoic-Holocene):

Acritarchs: organic-walled cysts of planktonic, marine dinoflagellates?

Hystrichospheres: tests of dinoflagellates.

20 to 200mm

Kingdom Animalia.

Phylum? Conodonta (C-Tr): toothlike phosphatic elements (part of presumed food processing apparatus in eel-like animal); nektonic, benthic, marine; probably concentrated in coprolitic associations. Many think these animals are chordates (vertebrates)
Phylum Porifera (Proterozoic to Holocene): siliceous sponge spicules in Cambrian to Holocene strata; benthic, marine (fossil record).
.
Phylum Arthropoda
Superclass Crustacea
Class Ostracoda (C-Holo): small bivalved crustaceans; marine, freshwater, terrestrial (in damp areas).