Geologic Time Scale for Kansas pdf. Geologic time: A metaphor Geologic periods in Kansas Eons and eonothems? Periods and systems? Understanding how geologists talk about time Mass extinctions Mass extinctions at the end of the Cretaceous Period Mass extinction at the end of the Permian Period. An artist's rendering shows hatchling nothosaurs heading for the safety of water as a hungry but terrestrial Ticinosuchus attacks near a lagoon in ancient Switzerland.
Nothosaurs lived during the mid- and late Triassic period and were among the earliest reptiles to take to the sea. Because nothosaurs may have had to come ashore to lay eggs, the eggs and hatchlings would have been vulnerable to Ticinosuchus. Yet once the hatchlings reached deeper waters, they were safe—for the moment. At the end of the Triassic, Earth warmed an average of between 5 and 11 degrees Fahrenheit, driven by a quadrupling of atmospheric CO 2 levels.
This was probably triggered by huge amounts of greenhouse gases from the Central Atlantic Magmatic Province, a large igneous province in central Pangaea, the supercontinent at the time. Remnants of those ancient lava flows are now split across eastern South America, eastern North America, and West Africa. The Central Atlantic Magmatic Province was enormous. Its lava volume could cover the continental U. The uptick in CO 2 acidified the Triassic oceans, making it more difficult for marine creatures to build their shells from calcium carbonate.
On land, the dominant vertebrates had been the crocodilians, which were bigger and far more diverse than they are today. Many of them died out. In their wake, the earliest dinosaurs—small, nimble creatures on the ecological periphery—rapidly diversified.
The Cretaceous-Paleogene extinction event is the most recent mass extinction and the only one definitively connected to a major asteroid impact. Some 76 percent of all species on the planet, including all nonavian dinosaurs , went extinct. One day about 66 million years ago, an asteroid roughly 7.
The massive impact—which left a crater more than miles wide—flung huge volumes of dust, debris, and sulfur into the atmosphere, bringing on severe global cooling. Wildfires ignited any land within miles of the impact, and a huge tsunami rippled outward from the impact. Overnight, the ecosystems that supported nonavian dinosaurs began to collapse. Global warming fueled by volcanic eruptions at the Deccan Flats in India may have aggravated the event. Some scientists even argue that some of the Deccan Flats eruptions could have been triggered by the impact.
Earth is currently experiencing a biodiversity crisis. Recent estimates suggest that extinction threatens up to a million species of plants and animals , in large part because of human activities such as deforestation, hunting, and overfishing. Other serious threats include the spread of invasive species and diseases from human trade, as well as pollution and human-caused climate change.
Explore National Geographic magazine's special issue on extinction. Today, extinctions are occurring hundreds of times faster than they would naturally. If all species currently designated as critically endangered, endangered, or vulnerable go extinct in the next century, and if that rate of extinction continues without slowing down, we could approach the level of a mass extinction in as soon as to years.
Climate change presents a long-term threat. By total volume, these past volcanoes emitted far more than humans do today; the Siberian Traps released more than 1, times the CO 2 than humans did in from burning fossil fuels for energy. As mass extinctions show us, sudden climate change can be profoundly disruptive. Well before hitting that grim marker, the damage would throw the ecosystems we call home into chaos, jeopardizing species around the world—including us. All rights reserved. Edaphosaurus A sail-backed edaphosaurus forages amid a Permian landscape in this artist's depiction.
Fleeing Nothosaurs An artist's rendering shows hatchling nothosaurs heading for the safety of water as a hungry but terrestrial Ticinosuchus attacks near a lagoon in ancient Switzerland. Share Tweet Email. Read This Next Wild parakeets have taken a liking to London. Animals Wild Cities Wild parakeets have taken a liking to London Love them or hate them, there's no denying their growing numbers have added an explosion of color to the city's streets.
India bets its energy future on solar—in ways both small and big. Environment Planet Possible India bets its energy future on solar—in ways both small and big Grassroots efforts are bringing solar panels to rural villages without electricity, while massive solar arrays are being built across the country. But why does extinction drive innovation?
Stable ecosystems may prevent innovation. Any experiments in carnivory would have ended badly, with the poorly adapted mammal competing with — or just eaten by — the already well-adapted Velociraptor. But, in the lulls after an extinction, evolution may be able to experiment with designs that are initially poorly adapted, but with long-term potential. The extinction of Velociraptor gave mammals the freedom to experiment with new niches.
They only needed to be as good as the other things around at the time. So they flourished in an ecological vacuum, ultimately evolving into big, fast, intelligent pack hunters.
Life will even recover from the current wave of human-induced extinctions. If we disappeared tomorrow, then species would evolve to replace woolly mammoths, dodo birds and the passenger pigeon, and life would likely become even more diverse than before.
This idea that extinction drives innovation may even apply to human history. The extinction of ice-age megafauna must have decimated hunter-gatherer bands, but it also may have given farming a chance to develop. The Black Death produced untold human suffering, but the shakeup of political and economic systems may have led to the Renaissance. Economists talk about creative destruction , the idea that creating a new order means destroying the old one.
When things are at their worst is precisely when the opportunity is the greatest. Portsmouth Climate Festival — Portsmouth, Portsmouth. Edition: Available editions United Kingdom.
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