GEOS 26400/BIOS 23255/EVOL 32300: Principles of Paleontology

Nature of the Fossil Record. I.
I. Kinds of fossils
      -fossil: any preserved remains of past life
      -body fossils: shells, teeth, etc.; also molds, casts, steinkerns
      -trace fossils

II. Factors of degradation (post-mortem)
      -biological destruction (scavenging, decomposition, bioturbation, boring, etc.)
            -role of burial & anoxia in fossil preservation
		-anoxia can result from high influx of dead material, with subsequent
		decomposition using up oxygen
            -role of early diagenetic mineralization in fossil preservation
      -mechanical destruction
            -wind, freeze-thaw, current, erosive particles etc.
            -general correlation between grain size and current velocity
      -chemical destruction
            -organic vs. inorganic preservation
            -environments of stability (Eh-pH fields)

III. Factors affecting preservability
      -organic/inorganic ratio
      -number of skeletal elements
      -specific mineral or organic composition
      -numerical abundance
      -habitat
      **A priori expectations require empirical testing

IV. Taphonomy
      -the study of fossilization processes
      A. Biostratinomy
      -generally covers changes prior to burial
      -example: Schopf's (1978) Friday Harbor study as attempt to predict
		quality (completeness) of local fossil record
      **Live-dead fidelity high for single taxonomic groups, but lower
      for mixed communities
	-Live-dead comparisons involve live fauna and contents of
		unconsolidated sediment (not necessarily what's in the fossil record)
	-Dead samples often contain more species than live census
		-more individuals sampled
		-temporal and spatial averaging
	-Benchmark of live-dead comparison is live-live comparison
		-live-dead agreement often as strong as agreement between
			repeated census of same living community

      B. Fossil diagenesis
      -generally covers changes after deposition, during and after lithification
      -replacement
      -petrifaction
      -permineralization
      -recrystallization
      -dolomitization
      -dissolution
      -distillation
      -distortion
      -different aspects of information in fossil affected by these processe