Taphonomy: The realm of paleontology dedicated to the study of the processes by which an organism becomes part of the fossil record. Yields an understanding of the filters and biases of the fossil record.

Becoming a fossil: From the birth of the organism to discovery by a paleontologist, fossils go through four general stages.

Biotic stage: Birth to death. The organism grows whatever tissue is capable of being preserved then dies. It has done its part. Whether it will become part of the fossil record depends on whether its carcass can remain intact long enough to be buried. The quicker the better because.....

Interment stage: Death to final burial. The carcass is exposed to:

Diagenetic stage: Final burial to discovery. Once buried, the remains are officially fossils, however their existence is still perilous. Diagenesis results in:

Investigative stage: Discovery to ultimate destruction. Every day, fossils are unearthed by erosion, only quickly to be destroyed by it. To enter the fossil record, as scholars understand it, a fossil must be exhumed (usually by natural processes), discovered, and described.

Not all clades of organisms produce preservable hard parts. Soft bodied organisms CAN produce fossils under special (konservat-lagersätten) situations to be considered later.

The compositional roster of these skeletons is non-random. Main hard substances found in organisms:

  • Calcite and/or aragonite - CaCO3 (calcareous hard parts dominate the fossil record).

    Calcareous skeletons are thought to have originated at least twenty times in eukaryote evolution. Also the first biomineral skeletons known, dating to 750 m.a. Typically secreted extracellularly. The abundance of independent origins suggests the exaptation (coopting) of an underlying biochemical mechanism present in soft-bodied precursors such as:

    List of some of the major clades producing common body fossils: (Classifications used here largerly follow these on the UMCP website)

    Phylogeny of skeleton-forming eukaryotes from Knoll, 2003.

    Organisms with silicious skeletons

    Radiolaria: (Cambrian - rec.)

  • Planktonic, microscopic
  • Opaline (i.e.hydrated silica) skeletons
  • Biostratigraphically significant? - Yes
  • Volumetrically significant? - No
  • Significant binder of sediment? - No

  • Bacillariophyta, better known as diatoms: (Jurassic - rec.)

    Organisms with calcareous skeletons

  • Foraminfera: (Cambrian - rec.)

    Chlorophyta green algae:

  • Coccolithophorida: (Jurassic - rec.)

  • Dinoflagellata: (Neoproterozoic - rec.)

    Cnidaria (corals)(Ediacaran - rec.) Most cnidarians, including jellyfish, hydras, etc, have no hard parts. Those that do are termed "corals" although this groups has evolved hard tissues several times.

    Bryozoa: (Ordovician - rec.)

    Mollusca: (Cambrian - rec.)

    Echinodermata: (Ediacaran - rec.)

    Organisms with phosphatic skeletons

    Vertebrata and relatives: (Cambrian - rec.)

    Organisms with diverse skeletal materials

  • Plantae: (Ordovician - rec.)

    Porifera (sponges): (Cambrian - rec.)

    Brachiopoda: (Cambrian - rec.)

    Arthropoda: (Cambrian - rec.)

    To Syllabus.

    Last modified: September 3, 2010