Intro

• Kingdom

  Phylum

  Class

  Order

  Family

  Genus

  Species
• Biological Processes

  Decay, Scavenging
• Physical Processes

  Damage to hard parts due to transport or collision with other debris
• Chemical Processes

  Dissolution of minerals by ground-water, replacement
• Replacement


  atom by atom replaced with new precipitated mineral
• Examples of Replacement

  Silicification, Pyritisation
• Calcite and Aragonite are Polymorphs- what is a Polymorph?


  Same Chemical Composition but have a different crystal form or shape
• What is Evolution


  The process by which inherited characteristics of a population are passed from parent to offspring
• Darwin-Wallace Theory

  • Based mostly on living species
  • Random variations resulting from crossbreeding and mutations are advantageous
  • individuals are more likely to pass these characteristics to their offspring
  • changes spread in the population
  • leads to a new species
• The Darwin-Wallace Theory is also know as Phyletic Gradualism
• Why Does Fossil Evidence NOT help prove Phyletic Gradualism

  • Fossil preservation is rare
  • full of gaps
  • soft tissue is rarely preserved
  • DNA only present for a short time
• What is the Punctuated Equilibrium Model?

  • A lot of evolutionary change takes place in a short period of time
  • then there is very little change for a long period of time
• Stages of Punctuated Equilibrium

  1. Stasis
  2. Isolation
  3. Strong selection and rapid change
  4. No preservation
  5. Reintroduction
  6. Expansion and Stasis
  7. Preservation
• Phyletic Gradualism


  Survival of the fittest. Gradual change but not much support In fossil record
• Punctuated Equilibrium


  Long periods of Stasis then a sudden change not captured by the fossil record
• General Principle


  Life gets more diverse and complex with time as their are more opportunities for evolution to occur
• Diversity will increase due to expansion into new habitats and also increased competition
• Diversity = Evolution - Extinction
• Sepksoski’s Curve shows marine diversity
• 3 Groups of Marine Organisms

  Cambrian Fauna, Paleozoic Fauna, Modern Fauna
• Cambrian Fauna

  • Mainly Trilobites and other arthropods
  • Mostly Mud eaters
  • Most lived on surface
  • Oversymplified (Burgess Shale)
• Paleozoic Fauna

  • Mainly Corals, Branchiopods & Predatory Cephalopods
  • Lived on and above the sea bed
  • Reefs
  • Filter Feeders and Foragers
  • Large predatory pressure - Decline in Cambrian Fauna
• Modern Fauna

  • Bivalves, Gastropods & Vertebrates
  • Burrowing and Predators are very common
  • Increased Mode of life
• Anthropocene


  Period of time during which human activities effect the environment enough to constitute a distinct geological period