IMPORTANT INVERTEBRATE FOSSILS IN INDIAN STRATIGRAPHY

Important Vertebrate Fossils In Indian Stratigraphy

The Causes Of Mass Extinctions:

• Mass extinctions are key episodes in Earth's history in which a great number of species die out in a short period of time.
• Understanding these occurrences is essential for comprehending the processes of

biodiversity, evolution, and ecological equilibrium.

1. Mass Extinction

• A mass extinction is defined as the abrupt extinction of at least 75% of a species worldwide.
• Historical context: Five significant mass extinctions have shaped the evolution of life on Earth.

2. The Big Five Mass Extinctions

1. The Ordovician-Silurian Extinction occurred around 443 million years ago

• Cause: climate change and sea level decline.
• Impact: Approximately 85% of species, including many marine species, were gone.

2. The Late Devonian Extinction occurred around 375 million years ago.

• Possible causes include climatic changes, low oxygen levels, and asteroid strikes.
• Approximately 75% of species were wiped off, resulting in substantial impacts on marine life.

3. The Permian-Triassic Extinction occurred around 252 million years ago

• Causes include volcanic eruptions, climatic change, and ocean anoxia.
• The most devastating extinction, with around 96% of all species going extinct.

4. Triassic-Jurassic Extinction (around 201 million years ago)

• Causes: volcanic activity and climate change.
• About 80% of species died, making room for dinosaurs.

5. The Cretaceous-Paleogene Extinction occurred around 66 million years ago

• Cause: meteor impact and volcanic activity
• Around 75% of species, including dinosaurs, were destroyed.

3. The causes of mass extinction

• Mass extinctions can be caused by a multitude of factors, which are frequently connected. Primary considerations include:

1. Environmental Change

• Climate Change: Temperature changes can impact ecosystems and food supplies.
• Sea level fluctuations can harm coastal and marine habitats.
• High CO2 levels cause ocean acidification, negatively impacting marine life.

b. Asteroid impacts

• Impact craters indicate that asteroid or comet encounters can cause catastrophic extinction.
• The Chicxulub impact played a crucial role in the dinosaur extinction.

• Volcanic Activity: Large eruptions can cause climate change and habitat destruction
• The Siberian Traps eruption was related to the Permian-Triassic extinction.

3. Biological Factors

• Invasive species have the potential to outcompete native species in new settings
• Disease outbreaks can devastate populations, especially if species are not resistant.

4. Impact on Biodiversity

• Loss of biodiversity can make ecosystems more vulnerable and less responsive to change.
• The extinction of one species can set off a chain reaction impacting many others.

 SOURCE

IMAGE SOURCE (THUMBNAIL)