5 Major Extinctions: Unraveling Earth’s Pivotal Crises

Mass extinctions are abrupt events that drastically reshape global biodiversity, involving major species losses.

Understanding Mass Extinctions

Mass extinctions are significant events in Earth’s history where substantial numbers of species disappear from the fossil record.

Rather than occurring at the steady pace of background extinction, these events are abrupt and have had transformative effects on global biodiversity.

Throughout the geologic time, at least five major mass extinction events have shaped the trajectory of life on the planet.

The Ordovician-Silurian extinction, around 440 million years ago, decimated 85% of marine species.

The causes are thought to be linked to climate change and falling sea levels.

Then, during the late Devonian Period, 375 million years ago, another event caused severe losses, particularly among marine life.

Fast forward to 250 million years ago, the Permian-Triassic extinction, or “The Great Dying,” witnessed the loss of around 96% of marine species and 70% of land species.

Scientists attribute this event to massive volcanic eruptions and resultant greenhouse effects.

The Triassic-Jurassic extinction about 200 million years ago cleared the way for dinosaurs to dominate.

The event’s origins remain debatable, but it could involve climate changes from volcanic activity or asteroid impacts. The most famous mass extinction occurred 66 million years ago, the Cretaceous-Paleogene extinction, ending the reign of dinosaurs.

An asteroid impact is the widely accepted cause, leading to drastic climate changes and disruption of ecosystems.

These cataclysmic events, while harsh, eventually led to the emergence of surviving species that adapted to the changed environments.

These episodes of biodiversity loss are crucial for understanding both ancient and contemporary species extinctions.

They also illustrate the resilience and adaptability of life in the face of dramatic environmental upheavals.

For more on the effects and causes behind these events, one can explore detailed discussions at Understanding Evolution by the University of California Museum of Paleontology and further coverage at Live Science.

Major Extinction Events

The earth is littered with the remains of ancient creatures, as the landscape is transformed by massive volcanic eruptions and asteroid impacts

The history of Earth is marked by catastrophic mass extinction events, each reshaping the balance of life.

These eras of significant species loss have greatly influenced the evolutionary path of surviving life forms.

Late Ordovician Mass Extinction

During the Late Ordovician mass extinction, approximately 85% of marine species vanished.

The event was likely triggered by a short, severe ice age that lowered sea levels, disrupting habitats.

This period saw a massive loss of marine life, including brachiopods and trilobites, and is one of the earliest known extinction events.

Late Devonian Extinction

The Late Devonian extinction over approximately 20 million years saw significant losses, particularly in the marine realm.

Environmental changes and volcanic activity potentially caused widespread anoxia, affecting marine animals like placoderms and coral reefs.

It was a drawn-out event, resulting in high extinction rates for marine species.

Permian-Triassic Extinction Event

The Permian-Triassic extinction event, known as the “Great Dying,” occurred around 252 million years ago.

Volcanic eruptions from the Siberian Traps led to catastrophic climate change, wiping out an estimated 96% of marine species and 70% of land species.

This event severely altered Earth’s ecological balance, leading to a long recovery time for the evolution of new species.

Triassic-Jurassic Extinction Event

The end of the Triassic period around 201 million years ago marks another mass extinction event that cleared the way for dinosaurs’ dominance during the Jurassic.

Several factors likely contributed, including climate change, volcanic eruptions, and an increase in greenhouse gases causing ocean acidification.

A variety of terrestrial and marine species were lost, paving the path for new species to fill the vacated ecological niches.

Cretaceous-Paleogene Extinction Event

The Cretaceous-Paleogene extinction around 66 million years ago is infamous for the demise of the non-avian dinosaurs.

Evidence suggests that a catastrophic asteroid impact caused immediate and long-term environmental effects.

This event led to drastic changes in the planet’s climate, ensuing global darkness and a collapse of the food chain that dramatically affected both land and marine species.

It ultimately made way for mammals to become the dominant land animals.