Mass Extinctions: Earth's Transformative Moments by Christian Francis

christia_f — 2024-02-27 04:14:40 UTC

During the Ordovician period, spanning 485 to 444 million years ago, Earth experienced a surge in species diversity followed by the first major mass extinction. Triggered by massive glaciation likely caused by the rise of the Appalachian Mountains, the planet cooled drastically. This led to a drop in sea levels, shrinking habitats for marine life. As sea levels rose again, marine oxygen levels decreased, causing toxic metal retention in ocean waters. This event, the second worst mass extinction in history, wiped out around 85 percent of species, with marine organisms like corals, brachiopods, conodonts, and trilobites bearing the brunt. Despite the devastation, life slowly recovered in hostile waters over time.

christia_f — 2024-02-27 04:16:34 UTC

Around 383 million years ago, a series of extinction events unfolded over roughly 20 million years, wiping out about 75 percent of Earth's species. During the Devonian period, decreased ocean oxygen levels occurred in pulses, notably the Kellwasser event around 372 million years ago, leading to significant losses in reef-building creatures and sea sponges. Potential triggers for these extinctions include volcanic activity like the Viluy Traps eruption and asteroid impacts such as the formation of the Siljan crater. Surprisingly, land plants may have accelerated rock weathering, causing nutrient influx into oceans, algae growth, and the formation of dead zones, while also impacting atmospheric CO2 levels and global cooling. Additionally, a slowdown in species diversification during the Devonian may be linked to the global spread of invasive species facilitated by high sea levels, enabling previously isolated marine habitats to mix.

christia_f — 2024-02-27 04:17:53 UTC

The key factor about a mass extinction is that it is one in which abnormally high numbers (compared to the background or normal extinction rate) of species die out at the same time.

Cretaceous Paleogene extinction-66 million years ago

miroslavs — 2024-02-27 04:19:48 UTC

Mass extinction that occurred about 66 million years ago, at the boundary of the Cretaceous and Paleogene periods. This extinction ended the Mesozoic era and began the Cenozoic era, which continues to this day. Most scientists support a hypothesis in which the fall of an asteroid plays a decisive role in the biological catastrophe that occurred. The impact with Earth ejected more than 50,000 km3 of rock in the form of dust and larger particles, ~325 gigatons of sulfur, and 425 gigatons of carbon dioxide and other volatile compounds. This abundance of sulfur and carbon is explained by the fact that at the point of impact there were layers of marine sediments with a high content of carbonates and sulfates. The impact itself generated a powerful blast wave and rains of molten and frozen rock fragments, destroying all life for thousands of kilometers around. In the years that followed this cataclysm, excess nitrogen and sulfur from the atmosphere turned into nitric and sulfuric acid, causing the oceans to become more acidic. Clouds of dust particles and aerosols raised into the atmosphere, despite the addition of “greenhouse” carbon dioxide, led to the effect of nuclear winter - a global drop in temperature due to a decrease in the permeability of the atmosphere to sunlight. This caused a catastrophic decline in the bioproductivity of the oceans and land and led to the extinction of ~75% of species of living organisms.

alejandrah1 — 2024-02-27 04:23:40 UTC

Over about 60,000 years, 96 percent of all marine species and about three of every four species on land died out, swell as wiping pout most insects. The world’s forests were wiped out and didn’t come back in force until about 10 million years later, and marina ecosystems took four to eight million years to recover .The biggest cause is the Siberian Traps, an immense volcanic complex that erupted more than 720,000 cubic miles of lava across what is now Siberia. The eruption t released at least 14.5 trillion tons of carbon.magma from the Siberian Traps infiltrated coal basins on its way toward the surface, probably releasing even more greenhouse gases such as methane causing global temperatures. 250.5 million years ago, sea surface temperatures at the Equator got as high as 104 degrees Fahrenheit. As temperatures rose, rocks on land weathered more rapidly, hastened by acid rain that formed from volcanic sulfur. The oceans lost an estimated 76 percent of their oxygen inventory. The models suggested rear age warming and oxygen loss is what causes most of extinction and species losses.

2024-02-27 04:24:28 UTC

The Cretaceous-Paleogene extinction is the most recent mass extinction and also the only one that can be definitely traced back to an asteroid impact. The asteroid resulted in the extinction of 76% of the animals that inhabited the planet at the time. The asteroid was 7.5 miles across and was thought to have impacted the Earth somewhere around Mexico's Yucatan Peninsula at approximately 45,000 miles per hour. As a result of the debris and other aftermath of the asteroid, as a consequence a global cooling commenced, additionally there were also wildfires up to 900 miles away from the land that was impacted and a tsunami flowed outward as well.

christia_f — 2024-02-27 04:39:32 UTC

Following the recovery from the Great Dying, life flourished with diverse reef-building creatures and lush vegetation, leading to the emergence of archosaurs around 201 million years ago. However, this era was marked by another significant extinction event at the end of the Triassic period, triggered by a dramatic increase in atmospheric CO2 levels due to volcanic activity from the Central Atlantic Magmatic Province. This led to widespread environmental changes, including ocean acidification, impacting marine life's ability to build shells and resulting in the decline of dominant crocodilian species. In this altered landscape, smaller and more agile dinosaurs rapidly diversified, emerging as dominant terrestrial vertebrates.

Science Daily: Has Earth's sixth mass extinction already arrived?

2024-02-27 04:44:33 UTC

Researchers used fossil records in order to formulate a comparison between past animal extinctions (specifically the past 5 mass extinctions taking place within the past 540 million years) with the extinctions of today. The researchers found that although the rate of extinction is in fact higher during this mass extinction than in the past, we haven't yet lost nearly as many species.

Many scientists studying this topic believe that the mass extinction could reach its peak at anywhere from 3 to 22 centuries. It is also made quite apparent that one of the primary methods of preventing this mass extinction from reaching its tipping point would be to attempt to prevent the affects of global warming.

Although there is still hope to reverse the issue seeing as only 1-2% of the species that had been apart of the research groups had actually been seen to have gone extinct. But the issue is still a large cause for concern even if the magnitude is low, because of the fact that the present rates are still higher than that of past mass extinctions.

One cofounding variable for the research being conducted for this topic is that the dating of fossil records is not always precise and therefore makes it hard to determine exactly when the animal went extinct, for what reason and also the significance of the impact that caused their decease.