Fossils Slideshow

Fossils

  • Authors: Sahasra N. and Shreya M.

Fossil Formation

  • Conditions for preservation of organisms:

    • Must be in an environment protected from oxidation and bacterial decay.

      1. Rapidly buried by sediment.

      2. Shielded from oxygen (anaerobic or anoxic conditions).

Biological Classifications

  • Mnemonic: Dorky King Phillip Came Over For Good Soup

    • Domain

    • Kingdom

    • Phylum

    • Class

    • Order

    • Family

    • Genus

    • Species

Modes of Preservation

  • Fossilization methods include:

    • Replacement

    • Unaltered/Actual remains

    • Mummification

    • Encasement in amber

    • Freezing

    • Tar preservation

    • Petrification/Petrifaction/Silicification

    • External molds

    • Casts

    • Internal molds

    • Imprint/Trace fossils

    • Carbonization/Coalification

    • Recrystallization/Altered remains

Types of Imprint/Trace Fossils

  • General types include:

    • Trace fossils

    • Trails

    • Tracks

    • Boring

    • Burrow

    • Tubes

    • Predation marks

    • Coprolites

Distortion of Fossils

  • Possible alterations during fossilization:

    • Crushed

    • Melted

    • Moved

    • Eroded

    • Shifting

Modes of Life (VERY IMPORTANT!)

  • Types of organisms based on lifestyle:

    • Pelagic

    • Sessile

    • Benthic

    • Vagrant

    • Motile

    • Coiled

    • Planktonic

Time Periods AND MAJOR EVENTS

  • Major geological timescales:

    • Supereon:

      • Precambrian

    • Eons:

      • Hadean

      • Archean

      • Phanerozoic

    • Eras:

      • Paleozoic

      • Mesozoic

      • Cenozoic

    • Periods

'Big Five' Mass Extinctions in Earth's History

  • A mass extinction is defined by the loss of at least 75% of species in a brief geological period (around 2 million years).

    • Extinction events:

      1. End Ordovician (444 Mya) - 86% species lost.

      2. Late Devonian (360 Mya) - 75% species lost.

      3. End Permian (250 Mya) - 96% species, 57% general families extinct.

      4. End Triassic (200 Mya)

      5. End Cretaceous (65 Mya) - 76% species lost overall, 40% genera, 57% families extinct.

  • Future extinction rates are influenced by human actions.

  • Natural extinction is part of evolution, with a background rate typically less than 5 families extinct per million years.

Dating and Principles

  • Methods for dating fossils and understanding geological time:

    • Index fossils (VERY IMPORTANT)

    • Relative Dating (VERY IMPORTANT)

      • Principle of Superposition

      • Principle of Original Horizontality

      • Principle of Cross-Cutting Relationships

      • Principle of Inclusions

    • Absolute Dating:

      • Half-life

      • Radiometric Dating

Modes of Life/mobility Pt. 1

  • Benthonic/Benthic organisms:

    • Infaunal: Live within sea/lake bottom sediment (e.g., burrowing clams, worms).

    • Epifaunal: Live on top of substrate/sediment (e.g., barnacles, sea stars).

    • Sessile: Fixed in place (e.g., corals, sponges).

    • Vagrant: Move or crawl on the substrate (e.g., some sea cucumbers, crabs).

Modes of Life/mobility Pt. 2

  • Planktonic/Planktic organisms:

    • Planktonic: Drift in the water column, cannot swim against currents (e.g., phytoplankton, zooplankton).

    • Nektonic/Nektic: Active swimmers (e.g., fish, whales, squid).

    • Terrestrial: Live on land (e.g., humans, trees, insects).

Ecological Roles

  • Major roles in ecosystems:

    • Producers

    • Filters/Suspension feeders

    • Predators

    • Scavengers

    • Deposit feeders (detritivores)

Kingdoms (memorize basic info and general appearance)

  • Protozoa

  • Animalia

  • Plantae