• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer
  • About
  • Image & Use Policy
  • Translations
  • Glossary

SUPPORT UE

  • Email
  • Facebook
  • Twitter

UC MUSEUM OF PALEONTOLOGY

UC Berkeley logoUC Berkeley

Understanding Evolution

Understanding Evolution

Your one-stop source for information on evolution

Understanding Evolution

  • Home
  • Evolution 101
    • An introduction to evolution: what is evolution and how does it work?
      • 1_historyoflife_menu_iconThe history of life: looking at the patterns – Change over time and shared ancestors
      • 2_mechanisms_menu_iconMechanisms: the processes of evolution – Selection, mutation, migration, and more
      • 3_microevo_menu_iconMicroevolution – Evolution within a population
      • 4_speciation_menu_iconSpeciation – How new species arise
      • 5_macroevo_menu_iconMacroevolution – Evolution above the species level
      • 6_bigissues_menu_iconThe big issues – Pacing, diversity, complexity, and trends
  • Teach Evolution
    • Lessons and teaching tools
      • Teaching Resources
      • Image Library
      • Using research profiles with students
      • Active-learning slides for instruction
      • Using Evo in the News with students
      • Guide to Evo 101 and Digging Data
    • Conceptual framework
      • Alignment with the Next Generation Science Standards
      • teach-evo-menu-icon
    • Teaching guides
      • K-2 teaching guide
      • 3-5 teaching guide
      • 6-8 teaching guide
      • 9-12 teaching guide
      • Undergraduate teaching guide

    • Misconceptions about evolution

    • Dealing with objections to evolution
      • Information on controversies in the public arena relating to evolution
  • Learn Evolution

Home → Mass extinction → What are mass extinctions?

    What are mass extinctions?

    Mass extinctions occur when global extinction rates rise significantly above background levels in a geologically short period of time. You can see these spikes in extinction rates in the graph shown at right. This graph shows extinction rates among families of marine animals over the past 600 million years. While background extinction levels hover around five families per million years, during mass extinctions, these rates shoot up.

    Mass extinctions can also be observed by looking at diversity levels over time. The graph below shows number of marine genera alive at different points in life’s history. While diversity levels generally increase over time, mass extinctions cause sudden drop-offs in diversity. The largest mass extinctions in Earth’s history are marked on this graph. Here, we will refer to each mass extinction by the name of the geologic period that it ended (e.g., the end-Ordovician extinction marks the end of the Ordovician period around 440 million years ago). During several of these events (notably, the Devonian and Triassic extinctions), low speciation rates also contributed to the loss of diversity. Biologists estimate that each of these mass extinctions correspond to a loss of ¾ of the species on Earth at the time!3

    3Jablonski, D. 1994. Extinctions in the fossil record. Philosophical Transactions of the Royal Society B 344:11-17.

    Bottom graph adapted from Figure 1 in Sepkoski, J.J. 1997. Biodiversity: past, present, and future. Journal of Paleontology 71:533-539.

    Previous

    Mass extinction

    Next

    Detecting mass extinctions in the fossil record

    Primary Sidebar

    Previous
    Next

    Mass extinction

    • What are mass extinctions?
    • Detecting mass extinctions in the fossil record
    • The role of mass extinction in evolution
    • Correcting common misconceptions about mass extinctions
    • Studying mass extinctions
    • Gathering evidence to study mass extinctions
    • What causes mass extinctions?
    • Volcanic activity and mass extinction
    • The Earth’s sixth mass extinction?
    • Credits

    Footer

    Connect

    • Email
    • Facebook
    • Twitter

    Subscribe to our newsletter

    Teach

    • Teaching resource database
    • Correcting misconceptions
    • Conceptual framework and NGSS alignment
    • Image and use policy

    Learn

    • Evo 101
    • Evo in the News
    • The Tree Room
    • Browse learning resources
    • Glossary

    Copyright © 2023 · UC Museum of Paleontology Understanding Evolution · Privacy Policy