6/21/2023 0 Comments Killed marine wildlife masse![]() Oceans acidified, and massive wildfires consumed entire ecosystems. Widespread volcanic activity across Siberia likely caused the largest mass extinction documented in the fossil record, the End-Permian. Read more: Marine Life Perished From the Late Devonian Mass Extinction Survivors included tetrapods, four-limbed animals that were transitioning from sea to land and would eventually evolve into reptiles, amphibians and mammals. What thrived: Little guys fared best, particularly vertebrates less than a meter long (about 3.3 feet). Many species of coral and more trilobites bit the dust, too. ![]() What died: Sadly, those awesome-looking armored fish known as placoderms were wiped out. How bad: About 75 percent of species and 35 percent of genera went extinct. ![]() The changes, possibly the result of significant volcanic activity in Siberia, reduced oxygen levels in the oceans and caused other environmental shifts. The End-Devonian, for example, consisted of a series of pulses in climate change over 20 million-plus years that led to periodic and sudden drops in biodiversity, including the Hangenberg Crisis, which some researchers consider a separate mass extinction event. Why: While the term mass extinction may suggest instant global catastrophe, these events can take millions of years. When: 359 million to 380 million years ago (Credit: Science History Images/Alamy Stock Photo) The placoderm lineage of ferocious-looking armored fish, such as Dinichthys herzeri, ended during the End-Devonian mass extinction, a long downward spiral in biodiversity. Read more: The End-Ordovician Mass Extinction Wiped Out 85 Percent of LifeĢ. The sponges stabilize sediment, creating a favorable environment for brachiopods and other suspension feeders. A 2017 Current Biology study suggests these humble marine animals may assist in the recovery of entire ecosystems. What thrived: Sea sponges did well in the aftermath of the End-Ordovician - a pattern repeated in subsequent mass extinctions. What died: Animals that didn’t make it include most trilobite species, many corals and several brachiopods, a hard-shell marine invertebrate often mistaken for a clam today. How bad: About 86 percent of species and 57 percent of genera - the next-higher taxonomic division, which may be a better gauge of biodiversity loss - went extinct. Many of the species that survived this first hit adapted to their new world, only to succumb to the second pulse: a sudden melt, another climate shift and another ocean circulation switch-up. Why: In the first pulse of a double whammy, ice sheets advanced, radically changing ocean currents and creating a harsh climate in the equatorial and mid-latitude regions. (Credit: Esteban De Armas/Alamy Stock Photo) Trilobites (foreground) got their start more than 520 million years ago, but faced their first decline during the End-Ordovician mass extinction. Theories that asteroid strikes initiate the massive die-offs remain largely speculative: Only one space rock has been conclusively linked to a mass extinction. While the catalysts of these events are sometimes unclear, large-scale volcanic activity, spread across an entire region, is a usual suspect. Great die-offs result from a perfect storm of multiple calamities, such as ocean acidification coupled with a spike in land temperatures. Researchers have enough data from the fossil record going back just over half a billion years to identify five such mass extinction events, and many scientists believe we’re in the middle of a sixth. These events are defined as the loss of least 75 percent of species in the geological blink of an eye - which can range from thousands to millions of years. Many evolutionary family trees got the ax, so to speak, during a mass extinction. That is, the 1 percent of species on Earth not yet extinct: For the last 3.5 billion or so years, about 99 percent of the estimated 4 billion species that ever evolved are no longer around. Congratulations, you’re part of the 1 percent.
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