Late Devonian Extinction

Definition

The Late Devonian Extinction refers to a significant biological crisis that occurred approximately 359 million years ago, resulting in the loss of about 70% of marine species, particularly affecting reef-building organisms. This extinction event is one of the five major mass extinctions in Earth's history and provides crucial insight into the temporal patterns of biodiversity and the resilience of ecosystems over geological timescales.

5 Must Know Facts For Your Next Test

1. The Late Devonian Extinction unfolded over a protracted period, spanning approximately 20 million years, indicating that extinctions were not instantaneous but part of a complex ecological shift.
2. This extinction event had multiple potential causes, including changes in sea levels, anoxic conditions in oceans, and possibly climate change that affected marine habitats.
3. Key groups affected included the placoderms (armored fish), trilobites, and many coral species, leading to significant changes in marine ecosystems.
4. Unlike other mass extinctions, the Late Devonian Extinction shows evidence of regional variations in extinction rates, suggesting that not all environments were equally impacted.
5. Following this extinction event, the recovery of marine life was slow, with ecosystems taking millions of years to rebound to their previous levels of diversity and complexity.

Review Questions

• How did the Late Devonian Extinction influence the structure of marine ecosystems in the following periods?
  • The Late Devonian Extinction dramatically altered marine ecosystems by significantly reducing biodiversity, particularly among reef-building organisms. This led to a decline in complex habitats that support various marine life forms. In subsequent periods, ecosystems had to rebuild from a diminished pool of species, influencing evolutionary pathways and resulting in new ecological dynamics as life adapted to the changed environments.
• Discuss the possible causes behind the Late Devonian Extinction and how they may have interacted with each other.
  • Several potential causes have been proposed for the Late Devonian Extinction, including significant fluctuations in sea levels, which may have disrupted habitats, and widespread anoxic events that led to oxygen depletion in oceans. Climate change could also have played a role by altering temperature and precipitation patterns. These factors likely interacted in complex ways; for instance, changing sea levels could influence ocean circulation patterns, exacerbating anoxic conditions and stressing marine life.
• Evaluate the long-term impacts of the Late Devonian Extinction on evolutionary processes in marine biodiversity.
  • The Late Devonian Extinction had profound long-term impacts on evolutionary processes within marine biodiversity. The extinction created new ecological niches and opportunities for surviving groups to diversify and adapt to changing environments. The loss of dominant taxa like placoderms allowed for the rise of new fish groups and eventually led to the development of more complex ecosystems. This shift underscores how mass extinctions can reshape evolutionary trajectories by removing established species while paving the way for new forms of life.

Related terms

Mass Extinction: A widespread and rapid decrease in the biodiversity on Earth, typically defined by the loss of at least 75% of species within a short geological timeframe.

Biodiversity Crisis: A significant reduction in biodiversity within an ecosystem or globally, often caused by factors such as climate change, habitat destruction, and pollution.

Extinction Rate: The rate at which species become extinct, which can vary widely across different time periods and is often influenced by environmental changes and human activities.