PALEONTOLOGICAL APPLICATIONS
Fossils as Clues to Ancient Environments
- PALEOECOLOGY
- The study of ancient organisms with their environment.
- Attempt to determine life habits of ancient organisms, what their habits and physical features
(morphology) reveal about past geography & climate.
- PALEOECOLOGY
- Organism adaptions reflect how it is designed for life and functions it can perform.
- Leaf shape and marginal features reflect climate conditions under which the plant
grows.
- Stomatal density reflects carbon dioxide concentration in atmosphere.
- PALEOCLIMATOLOGY
- Assemblages of pollen & spores provide basis for vegetational biomes present near any
depositional setting.
- Permineralized wood provide evidence of annual growth rings that reflect climatic
influence.
- PALEOCLIMATE
- Marine molluscs have particular traits found in tropical settings (spinosity & shell thickness).
- Skeletal composition may be assessed geochemically
- Marine organisms in warm waters have higher proportion of magnesium than in colder
areas.
- In colder realms there is a higher calcite-to-aragonite ratios (and vice versa).
- STABLE ISOTOPES & CLIMATE
- Evaporation of sea water enriches water with O18 (O16 is lighter and evaporates).
- STABLE ISOTOPES - OXYGEN
- When glaciers are present, they will be O16 enriched whereas ocean water will be O18
enriched.
- STABLE OXYGEN ISOTOPES
- Calcium carbonate crystallization in shells will reflect this O18 enrichment.
- Temperature-fractionation of O 18 used to build shells.
- If there has been no alteration in the shell, it is possible to calculate the original ocean
temperature at the time of shell formation.
- ANCIENT TROPHIC STRUCTURE
- Paleoecologists attempt to discern the interrelationships between primary producers (low
man on the trophic scale) and consumers (of a variety of trophic levels including herbivores
& carnivores).
- PALEOGEOGRAPHIC APPLICATIONS
- Identification of fossil assemblages and their ecological components allows for the
reconstruction of ancient landscapes (palaeogeography).
- APPLICATIONS TO PALEOGEOGRAPHY
- Biotic assemblages can aid in determining the ancient continental position relative to the
equator, parallels of latitude (but not longitude), and polar positions.
- Species diversity for higher taxonomic categories increases towards the equator and
decreases towards the poles.
- Such generalized biotic features provide a means to test palaeogeographies
reconstructed from independent data sets.
GE142