In summary... T. rex and the Crater of Doom

These days I spend most my time studying, reading and writing. I am far from a scientist, but occassionaly get to write summaries about scientists. Here's one I summarized that covers the destruction of the Dinosaurs:

In T. rex and the Crater of Doom, author Walter Alvarez describes the impact and aftermath of the comet that forever changed Earth as we know it.

An object taller than Mount Everest and about 10km in diameter slammed into the Earth at a velocity of perhaps 30 km per second. The comet vaporized on impact in about 1 second and left a crater 150-200km across at a depth of perhaps 40km. The comet left a crater pattern resembling a bull’s eye imprinted on the Yucatán Peninsula, the comet’s impact point. The impact essentially ended the Cretaceous period and was equivalent to the explosion of 10,000 times the entire nuclear arsenal of the world.

The comet entered the Earth’s atmosphere around 65 million years ago, and upon entry heated the air around it to a temperature 4 or 5 times that of the Sun. In the zone where bedrock was melted or vaporized, no living thing could have survived. The earth’s surface itself became an enormous broiler—cooking, charring, igniting, immolating all tress and all animals which were not sheltered under rocks or in holes. Even as the forests were set ablaze, another horror was approaching the coasts of the Gulf of Mexico.

The result was a gigantic tsunami a kilometer high. Within hours of the impact, most of Mexico and the United States must have been reduced to a desolate wasteland of the most appalling, agonizing destruction. Farther away from the Yucatan the effects were less dramatic.

But tragedy would unfold more slowly in these remote areas through the secondary effects of the impact. An enormous mass extinction followed. The Earth was turning cold and dark. The dust was settling through the upper atmosphere around the world, blocking the sunlight. Carbon dioxide can only be removed slowly from the air, and now it trapped the heat from the Sun, raising temperatures to sweltering levels, plus caused acid rain. A world first dark and frozen, then deadly hot, now a world poisoned by acid and soot.

Half of all living things, at the moment of the impact, perished. The biggest victims were the Dinosaurs. The loss of the dinosaurs is probably related to their position in the food chain. During the months of cold and darkness the herbivores would starve. Large animals are never abundant, especially top carnivores, so they would have been particularly vulnerable to extinction. The birds were nearly wiped out as well. Land plants, single-celled plants and animals also suffered nearly complete extinction. Marine animal losses were devastated but a few species survived and left descendants which abound in the oceans today. But many smaller land animals survived, including mammals and reptiles.

It marked the end of a world, yet the darkness eventually faded, the heat died down, and the acids were neutralized. Survivors found themselves in a new world. For 150 million years, dinosaurs had been the large land animals of the planet while mammals were confined, but with the disappearance of the dinosaurs there were new opportunities for mammals and evolution did not waste any time producing larger ones.

Because of this catastrophe, evolution embarked on a course which, 65 million years later, led to us. We are the beneficiaries of Armageddon.

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