Ordovician period

Definition

The Ordovician period is a significant geological time frame that occurred approximately 485 to 443 million years ago, following the Cambrian period and preceding the Silurian period. It is marked by a rapid diversification of marine life and the establishment of complex ecosystems, setting the stage for major evolutionary developments, including the rise of early fish and diverse invertebrate groups.

5 Must Know Facts For Your Next Test

1. During the Ordovician period, marine biodiversity significantly increased, with the emergence of various new species, particularly among brachiopods and bryozoans.
2. The first vertebrates appeared in the Ordovician, marking an essential step in fish evolution, with jawless fish like ostracoderms becoming more prominent.
3. The Ordovician is also known for extensive shallow marine habitats, with large reef systems formed by coral-like organisms and other marine fauna.
4. Major tectonic movements during this period contributed to changing sea levels and climatic conditions that influenced the distribution of marine life.
5. The end of the Ordovician period was marked by a significant extinction event, which saw a dramatic reduction in marine species and altered ecological dynamics.

Review Questions

• How did the Ordovician period contribute to the evolution of marine ecosystems and biodiversity?
  • The Ordovician period played a crucial role in enhancing marine biodiversity through a rapid diversification of species. Various new groups emerged, such as brachiopods and bryozoans, alongside early vertebrates. These developments fostered complex ecosystems where different organisms interacted, setting the foundation for future evolutionary pathways.
• In what ways did geological changes during the Ordovician influence marine life and habitat distribution?
  • Geological changes during the Ordovician, including tectonic shifts and varying sea levels, created diverse habitats that supported a wide range of marine life. The formation of extensive shallow seas and reefs allowed for more ecological niches to develop. This variation led to increased speciation as organisms adapted to different environments, showcasing how geology directly affects biological diversity.
• Evaluate the significance of the end-Ordovician extinction event on subsequent evolutionary trends within marine ecosystems.
  • The end-Ordovician extinction event had profound effects on marine ecosystems by dramatically reducing species diversity and altering ecological dynamics. This extinction paved the way for new groups to rise in prominence, significantly impacting evolutionary trajectories. The losses experienced during this event allowed surviving species to adapt and fill vacant ecological roles, shaping future ecosystems during subsequent geological periods.

Related terms

Cambrian Explosion:

A rapid evolutionary event around 541 million years ago that resulted in the emergence of most major animal phyla, leading into the rich biodiversity seen in the Ordovician.

Silurian period: The geological period following the Ordovician, which is characterized by further evolution of fish and the first land plants.

Graptolites: Extinct colonial animals that thrived during the Ordovician period, known for their distinctive fossilized remains, which help in dating rock layers.