The Cretaceous-Tertiary extinction event, or the K-T event, is the name given to the die-off of the dinosaurs and other species that took place some 65.5 million years ago. For many years, paleontologists believed this event was caused by climate and geological changes that interrupted the dinosaurs’ food supply. However, in the 1980s, father-and-son scientists Luis (1911-88) and Walter Alvarez (1940-) discovered in the geological record a distinct layer of iridium–an element found in abundance only in space–that corresponds to the precise time the dinosaurs died. This suggests that a comet, asteroid or meteor impact event may have caused the extinction of the dinosaurs. In the 1990s, scientists located the massive Chicxulub Crater at the tip of Mexico’s Yucatán Peninsula, which dates to the period in question.
Dinosaurs roamed the earth for 160 million years until their sudden demise some 65.5 million years ago, in an event now known as the Cretaceous-Tertiary, or K-T, extinction event. (“K” is the abbreviation for Cretaceous, which is associated with the German word “Kreidezeit.”) Besides dinosaurs, many other species of mammals, amphibians and plants died out at the same time. Over the years, paleontologists have proposed several theories for this extensive die-off. One early theory was that small mammals ate dinosaur eggs, thereby reducing the dinosaur population until it became unsustainable. Another theory was that dinosaurs’ bodies became too big to be operated by their small brains. Some scientists believed a great plague decimated the dinosaur population and then spread to the animals that feasted on their carcasses. Starvation was another possibility: Large dinosaurs required vast amounts of food and could have stripped bare all the vegetation in their habitat. But many of these theories are easily dismissed. If dinosaurs’ brains were too small to be adaptive, they would not have flourished for 160 million years. Also, plants do not have brains nor do they suffer from the same diseases as animals, so their simultaneous extinction makes these theories less plausible.
Answer:Tertiary
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+ Feminism: A Transformational Politic Hooks conclude should be the main concern for future feminist movements and the revitalization of feminist perspectives The central concern, hooks says, should not be to reinforce the paradigm of men as the enemy, but to “begin as women seriously addressing ourselves, not solely ...02-Dec-2019
America is at war. We have been fighting drug abuse for almost a century. Four Presidents have personally waged war on drugs. Unfortunately, it is a war that we are losing. Drug abusers continue to fill our courts, hospitals, and prisons. The drug trade causes violent crime that ravages our neighborhoods. Children of drug abusers are neglected, abused, and even abandoned. The only beneficiaries of this war are organized crime members and drug dealers.
<span>The United States has focused its efforts on the criminalization of drug use and trafficker's coming from Mexico. The government has spent billions of dollars trying to get rid the supply of drugs coming into our country. These intervention efforts and law enforcement attempts to control the drugs have not been successful nor have they met with decreases in the availability of drugs in America. There are actually more drugs now than ever before! Apart from being super expensive, drug law and drug enforcement has been counterproductive, it does not work. Our current drug laws need to be reviewed and revamped so that they are more effective or are a deterrent to those to bring drug into the US. The United States needs to shift spending from law enforcement and penalization to education, treatment, and prevention.</span>
