Late Devonian

Definition

The Late Devonian refers to a geological period that occurred around 383 to 359 million years ago, marking the final stage of the Devonian Period. This time is notable for significant ecological changes and a dramatic decline in biodiversity, often referred to as the Late Devonian extinction event, which is one of the five major mass extinctions in Earth's history.

5 Must Know Facts For Your Next Test

1. The Late Devonian extinction event is believed to have caused the loss of approximately 70% of marine species, significantly impacting oceanic ecosystems.
2. This extinction event primarily affected fish species, including both jawed and jawless forms, leading to a dramatic shift in aquatic biodiversity.
3. There is evidence suggesting that environmental factors such as changes in sea level, climate shifts, and anoxic events contributed to the biodiversity crisis during the Late Devonian.
4. The decline in biodiversity during this period allowed for the rise of new groups of organisms, such as early tetrapods and different types of amphibians in subsequent periods.
5. The Late Devonian is also known for the emergence of complex terrestrial ecosystems, with significant diversification among plants and the development of forests.

Review Questions

• What were the main ecological impacts of the Late Devonian extinction event on marine life?
  • The Late Devonian extinction event had profound effects on marine ecosystems, resulting in the extinction of about 70% of marine species. Among those most affected were various fish groups, leading to a significant reduction in diversity within oceanic habitats. This decline reshaped marine food webs and opened up ecological niches that allowed for new species to evolve and fill these gaps in later periods.
• Discuss the potential causes behind the biodiversity crisis during the Late Devonian period.
  • Several factors contributed to the biodiversity crisis during the Late Devonian period. Notably, environmental changes such as fluctuations in sea levels, shifts in climate leading to cooler temperatures, and anoxic events in ocean waters likely played significant roles. These conditions created inhospitable environments for many species and disrupted existing ecosystems, resulting in widespread extinctions across various marine taxa.
• Evaluate the significance of the Late Devonian period in shaping modern ecosystems and biodiversity.
  • The Late Devonian period was crucial in shaping modern ecosystems due to its role in one of Earth's major mass extinctions. The loss of many marine species opened opportunities for surviving groups to diversify and adapt, leading to evolutionary developments seen in later periods. This shift not only impacted aquatic life but also facilitated the rise of terrestrial plants and early tetrapods, setting the stage for future biodiversity patterns that influence today’s ecosystems.

Related terms

Mass Extinction: A widespread and rapid decrease in biodiversity on Earth, characterized by the extinction of a large number of species across various habitats.

Biodiversity: The variety of life in a particular habitat or ecosystem, encompassing the diversity of species, genetic variations, and ecosystems.

Fossil Record: The history of life as documented by fossils, providing evidence of past organisms and the changes in biodiversity over geological time.