Essay about Examining the Cretaceous: Paleogene Extinction Event
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Examining the Cretaceous–Paleogene extinction event Over 98% of all organisms that have lived on Earth are now extinct. A mass extinction event occurs when a large number of species die out within a small time frame (relative to the age of Earth). Mass extinctions are intensively studied for both cause and effect, as there is usually room for debate regarding catalysts that precede the extinction and the massive influx of new biological species that follows. There have been five major mass extinctions, dubbed the “Big Five,” that have wiped out at least 50% of the species living at those times. The most well known mass extinction of the Big Five, with the decimation of every species of non-avian dinosaur, is the Cretaceous-Paleogene…show more content… This final blow would have sent earth into a nuclear winter. According to this theory, dust caused by the asteroid collision disrupted plant growth by blocking out the sunlight needed for photosynthesis for nearly a year. A chain reaction occurred as plants died off, so did the herbivores relying on the plants, and then the carnivores that relied on the herbivores. Around 75% of species became extinct, including dinosaurs, mammals, giant marine lizards, fish, birds, and insects. Meanwhile, seawater flooded around 40% of the world’s continents ("Mass Extinctions").
However, such mass extinction opens up speciation – when new species are developed. After the K-Pg extinction, new groups of organisms were on the rise. Giant boid snakes (12 – 15 meters) began appearing on land and the teleost fish (diverse class of ray-finned fish) filled marine niches left vacant. Most significantly, “Paleocene mammals would spread and evolve into the many ecological niches left open by the extinction of the dinosaurs,” (“Cretaceous: Extinction of the Dinosaurs”). The entirety of Earth’s ecosystem was affected by the K-Pg extinction, caused by volcanoes, oceanic shifts, and ultimately, an asteroid. Lucky for humans, mammals capitalized on the opportunity