In 1881, Charles Darwin published an entire book on earthworms, writing, “It may be doubted whether there are many other animals which have played so important a part in the history of the world. THOUSANDS OF EARTHWORM SPECIES have shaped the planet’s soil chemistry, plant communities and even the atmosphere itself over hundreds of millions of years.
WAVE WILDLIFE MASSE PLUS
Photos by Kim Taylor/NPL (left) and DaveAlan/iStock/Getty Images Plus (right). Spreading through northern forests that evolved without earthworms, these animals can degrade forest soils and devour the seeds of trees and native plants such as trillium (right) that help support native wildlife. The widespread, invasive European earthworm (left) is distinguished by a dark band near its middle. The event is so striking that it signals a major turning point in Earth's history, marking the end of the geologic period known as the Cretaceous and the beginning of the Tertiary period.Invasive earthworms are spreading across the planet-transforming soils, gardens, forests and entire ecosystems in ways that may make you squirm. The extinction that occurred 65 million years ago wiped out some 50 percent of plants and animals. "C" is shorthand for an earlier period, the Cambrian. Why not C-T? Geologists use "K" as a shorthand for Cretaceous. Scientists refer to the major extinction that wiped out nonavian dinosaurs as the K-T extinction, because it happened at the end of the Cretaceous period and the beginning of the Tertiary period. Cretaceous-tertiary Extinction: 65 Million Years Ago What to Call It? The extinction of other vertebrate species on land allowed dinosaurs to flourish. Triassic-jurassic Extinction: 210 million years ago The largest mass extinction event in Earth's history affected a range of species, including many vertebrates. Permian-triassic Extinction: 250 million years ago Many tropical marine species went extinct. Devonian Extinction: 365 million years ago Top Five Extinctions Ordovician-silurian Extinction: 440 million years ago The largest mass extinction event happened around 250 million years ago, when perhaps 95 percent of all species went extinct. Mass extinctions-when at least half of all species die out in a relatively short time-have occurred only a handful of times over the course of our planet's history. A Brief History of EarthĮarly life forms began to flourish during the Cambrian Explosion, 540 million years ago. rex and Triceratops some 65 million years ago wouldn't be especially noteworthy-except for the fact that around 50 percent of all plants and animals alive at the same time also died out in what scientists call a mass extinction. Scientists estimate that at least 99.9 percent of all species of plants and animals that ever lived are now extinct. A wide range of animals and plants suddenly died out, from tiny marine organisms to large dinosaurs. Around 65 million years ago, something unusual happened on our planet-we can see it in the fossil record.įossils that are abundant in earlier rock layers are simply not present in later rock layers.
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