Mass Extinctions
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Mass Extinctions
Paleontolists (scientists who study past life) are bemused by the mass extinctions that occurred about 65 million years ago. About 75% of all species disappeared rather quickly, but not all species seemed threatened. Different hypotheses to explain the worldwide, catastrophic disappearances include a sudden, drastic cooling of the Earth, or a shift in the magnetic field that allowed harmful radiation to enter the atmosphere. But most paleontolists agree that massive extinctions such as these were probably a result of a tremendous disruption of the food chain. What would destroy the food chain on a worldwide basis? Some scientists suggest volcanic explosions from the Deccan plateau in India, but the currently popular theory is that a massive meteorite that landed off the coast of the Yucatan peninsula in Mexico may be to blame. The meteorite impact would have caused enormous amounts of dust to enter the atmosphere, which would block out sunlight and lower temperatures for years, causing plants to die off. When the plants died, plant-eating animals would have starved and ultimately died off. That in turn would have caused their predators to die. The importance of protecting the bottom of the food chain is an important point to remember, since media coverage today typically focuses on protecting those animals at the top of the chain, not the bottom.
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| Jennifer Mathes, Ph.D. |
