MONERA AND PROTISTA

Members of the Kingdom Monera are distinguished by their prokaryotic cells. They are unicellular, though often colonial. Those incapable of photosynthesis are typically called "bacteria"; many are anaerobic. Those which photosynthesize are called "Cyanobacteria" from the blue-green (=cyan) pigmentation resulting from their chlorophyll and other pigments. Virtually all are aerobic. Bacteria are the oldest known fossils, dating from about 4 by, and until about 3 or 2.5 by they are about all that are known. Cyanobacteria often form mats which may produce laminated and wavy-laminated beds called "stromatolites". They are common in late Archaean to Cambrian rocks (3-0.6 by) but in younger rocks are known only from highly stressed physical environments.

Members of the Kingdom Protista are also unicellular, often colonial, and are rather more important as fossils. Photosynthetic ones are informally called "algae", nonphotosynthetic ones are known as "protozoa". Algae are important fossils for two reasons:

1) Most carbonate mud in limestones, and some carbonate sand, are the remains of colonial calcareous algae.

2) Many planktonic (non-colonial) algae secrete shells of calcite or silica and make excellent guide fossils. The more important ones include, but are not limited to:

                    a) COCCOLITHS -- tiny calcareous golden-brown marine algae.

                    b) DIATOMS -- siliceous marine or freshwater golden-brown algae.

                    c) DINOFLAGELLATES and ACHRITARCHS -- resistant organic cysts.

The protozoa also include many important guide fossils. An outline of the classification of two important groups is:

KINGDOM PROTISTA

    PHYLUM PROTOZOA

        CLASS ACTINOPODA

            SUBCLASS RADIOLARIA -- Siliceous marine plankton

        CLASS SARCODINA

                ORDER FORAMINIFERA -- Marine calcareous or organic-walled benthos or plankton.

The forams are informally divided into:

Planktonic forams -- tiny, thin-walled species of global biostratigraphic importance.

Smaller benthic forams -- studied only with microscope, classified based on shell and aperture morphology. Used with great success in local biostratigraphy.  Particularly useful for well cuttings.

Larger benthic forams -- Easily visible. Studied by sectioning and examination of internal structure such as coiling, chamber connections, etc. Useful in local biostratigraphy of Mississippian (endothyrids), Pennsylvanian-Permian (fusulinids), and Jurassic-Recent rocks (many types such as nummulitids).

Formally, they are classified to suborder based on the structure of their shell wall, though absolutely nobody believes this has anything to do with their evolutionary relationships:

SUBORDER ALLOGROMINA -- Organic wall only. (Cambrian-Recent)

SUBORDER TEXTULARIINA -- Agglutinated wall. (Cambrian-Recent)

SUBORDER FUSULININA -- Granular calcareous wall. (Ordovician-Permian)

SUBORDER MILIOLINA -- Porcelaneous calcareous wall. (Pennsylvanian-Recent)

SUBORDER ROTALIINA -- Perforate glassy (hyaline) wall. (Permian-Recent)

Forams alternate a sexual with an asexual "generation" during their lives, and each stage has a separate, distinctive shell. Formerly many of these shell-type pairs were assigned to separate species because they look so different.

TERMS TO BE FAMILIAR WITH:

Agglutinated -- shell made of sand or other loose material "glued" together by the foram.

Aperture -- a relatively large terminal opening of the test. Useful in classifying smaller forams. (FIG)

Biserial -- Chambers are added on alternate sides of the test to produce a double row of chambers. (FIG)

Chamber -- Internal partitions in most species divide the test into smaller compartments or chambers.

Convolute -- Coiling arrangement in which each whorl completely encloses earlier whorls. (FIG)

Foramina -- Openings connecting the internal chambers together. Basis of the Order name.

Fusiform -- Shaped like a spindle, or a fat cigar, or a skinny football.

Involute -- Coiling arrangement in which each whorl partially overlaps the one before.

Keel -- A raised ridge running along the outermost arc of the outer whorl of a test.

Megalospheric -- Having a large proloculus. Results from asexual fission of a parent cell.

Microspheric -- Having a small proloculus. Results from sexual reproduction.

Perforate -- Test with many small openings, sometimes clearly visible, sometimes not.

Planispiral -- Coiled around an axis without translation along that axis, like a rope coiled flat on a boat deck.

Proloculus -- The initial chamber of a multilocular foram test.

Pseudopod -- Sarcodines have extensible cell membranes which are used primarily for locomotion. Think of the pictures of amoebas you've seen oozing along a microscope slide. Each projection is a pseudopod.

Spiral Suture -- The line of junction of each whorl with the one before it.

Suture -- The line of junction of the test wall with the internal partitions which separate chambers.

Test -- The skeleton of a protist. Differs from a "shell" in that it lies within a covering of soft tissue as well as enclosing soft tissue. Used for other types of organisms as well.

Trochospiral -- A spiral form which coils around an axis while "translating" along that axis, like screw threads.

Uniserial -- A multilocular test with the chambers arranged in single file.

Umbilicus -- A depression at the coiling axis of a convolute or deeply involute test.

PALEOECOLOGY

1) All forams (and radiolarians) are marine organisms.

2) Because radiolarians are much less abundant than forams, samples containing only Radiolaria were probably deposited in water deeper than the CCD, where calcite foram tests would be dissolved.

3) Abundant planktonic forams in a sample, coupled with paucity of benthic species, usually implies deep water, but shallower than the CCD.

4) Benthic forams have been used with great success in recognizing water depth. Typically, different assemblages of foram species occur at different water depths on a continental shelf. The same is apparently true of planktonic foram assemblages on a continental rise.

5) A greater proportion of calcareous tests, as opposed to agglutinated (Textulariina) and organic (Allogromina) probably indicates warmer water.

6) Larger benthics, such as nummulitids, are also more common in warmer water. In addition, many modern forams over a few mm in diameter have symbiotic relationships with green algae in their tissues, and so live well within the photic zone (<100m, usually). The same is likely to have been true of the nummulitids and certain other larger forams.

BIOSTRATIGRAPHY

1) Foraminifera range from the Cambrian to the Recent (see ranges of each Order above). They are used to varying degrees in biostratigraphic zonation of rocks from Ordovician to Recent age. Particularly useful groups are as follows:

2) Rather small benthic fusulinines of the Superfamily Endothyracea have been used with great success to zone Mississippian rocks. They are useful on a local or (paleo)continental scale.

3) Larger fusiform fusulinines of the Suborder Fusulinacea are the primary invertebrates used in zonation of Pennsylvanian and Permian rocks. They are also useful at the local and (paleo)continental scale.

4) Benthic forams of various types are very useful in zoning Mesozoic and Cenozoic rocks. Perhaps the most famous are the nummulitids which are so common around the Mediterranean that the Eocene and Oligocene were originally called the "Nummulitic Epoch" in Europe, Asia, and Africa.

5) Planktonic forams are one of the principal guide fossils used in global correlation. Their planktonic habit means they are a) widely dispersed, and b) likely to settle into essentially any sedimentary facies.