Cretaceous KT Mass Extinction million years ago

Boundary Iridium

Mass extinction is known by the boundary between one geologic time period and the next. The Cretaceous mass extinction, better known as the K-T mass extinction, happened at the boundary between the Cretaceous Period and the Tertiary Period. The K stands for Kreide, which is the German word for chalk. It An iridium layer has been found at the K-T boundary in more than 100 different places around the world. An iridium layer has been found at the K-T boundary in more than 100 different places...

Fossils Our Clues to the Past

How do scientists know what the world looked like millions of years ago How do they know dinosaurs even existed They learn by studying fossils, the remains of living animals and plants from the past. Fossils are preserved in certain rocks and sometimes in other materials, such as amber (hardened tree sap). Scientists called paleontologists rely on the fossil record to tell us how ancient animals and plants lived. How does a living thing become a fossil It can happen in several different ways....

Warp Speed Extinction

Throughout life's history, there has always been a low level of extinction. This is called background extinction. It is like low music playing while you do your homework. As species die off, new species evolve a bit faster. The fossil record shows how the diversity of life has always increased. Mass extinction is very different from background extinction. It is like a sudden, startling blare of music. Many species suddenly die, and new species do not evolve fast enough to take their place....

For the Next Mass Extinction

M r ight now, we may be in the middle of a mass extinction that could be bigger than the one that killed off the dinosaurs. Like all life, humans are a species on an endless path of evolution. If there is an empty space on the planet, we rush to fill it. Today, humans live in every corner of the globe. We are not the most numerous species. There are millions more insects than there are humans. We are not the oldest species. Cockroaches have roamed the planet for much longer than we have. Every...

Mass Extinctions of the World

In a mass extinction, a large number of all species vanish within a short period of time. According to the fossil record, there have been at least ten mass extinctions throughout Earth's exis- Devonian (Age of Fishes) 408-360 mya 3.8 BILLION years ago LIFE BEGINS IN OCEANS -4.5 BILLION years ago BIRTH OF EARTH APPROX. YRS. AGO (mya millions of years ago) 3.8 BILLION years ago LIFE BEGINS IN OCEANS -4.5 BILLION years ago BIRTH OF EARTH tence. The five biggest examples were during the Ordovician...

Is The Asteroid Theory the Final Word

The Alvarez team now had a great deal of evidence to answer the question, What killed the dinosaurs All over the world, high levels of iridium, tektites, shocked quartz, soot, and ash were found in rocks dating from the K-T boundary. In addition, a crater was found that matched the size of an asteroid large enough to cause a mass extinction. These findings support an asteroid theory of mass extinction. New evidence suggests that more than one asteroid hit the planet around 65 million years ago....

Great Extinctions of the Past

Scientific American Great Extinctions of the Past Scientific American is a registered trademark of Scientific American, Inc. Its use is pursuant to a license with Scientific American, Inc. All rights reserved. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval systems, without permission in writing from the publisher. For information contact An imprint of Infobase...

Extreme Heat and Suffocation

This recent view sees the Permian mass extinction as a series of extinctions. Each extinction set off another one in a chain reaction. The massive volcanic eruptions in Siberia may have been the first part of this Permian chain reaction. These eruptions may have increased the world's temperature by releasing huge amounts of heat and molten lava. The volcano also released thick clouds of carbon dioxide. Carbon dioxide acts like a blanket that traps warm air on the surface of the planet. As...

The Clock of Extinction

Sedimentary rocks and the fossils they contain make up a sort of calendar called the Geologic Time Scale. This scale shows the history of life on our planet, beginning with the birth of Earth 4.5 billion years ago. Since the 1800s, geologists have used the Geologic Time Scale to describe Earth's history. The timeline is divided into eras and periods. (An era is broken down into several shorter spans of time called periods.) For example, the dinosaurs lived during the Mesozoic Era, which began...

The Great Dying Permian Mass Extinction million years ago

Pre Paleozoic Animals

Life flourished for more than 100 million years after the Devonian mass extinction. Reptiles appeared. These were the early ancestors of the dinosaurs, yet they were not the strongest creatures on the planet. During this time, mammal-like reptiles called gorgons were the most powerful reptiles on the planet. These ferocious creatures looked half-lion and half-dragon. Then, the largest extinction in Earth's history took place. It happened at the end of the Permian Period around 250 million years...

Survival of the Fittest

Many times, several species will try to move into an empty niche at the same time. There is only so much food and space to go around. Species constantly compete with each other for space and resources. Only the most adaptable species will win out and get to stay in this new home. If a species cannot adapt to another habitat, it becomes extinct. This is known as survival of the fittest. Along with natural selection, it is another important part of the theory of evolution. A species that becomes...

Bibliography

The Dinosaur Heresies. New York Zebra Books, 1986. Basu, Asish, and Paul R. Renne. Massive Volcanic Eruptions in Siberia Links to Largest Extinction. Benton, Michael. Accuracy of Fossils and Dating Methods. Boulter, Michael. Evolution and the End of Man. New York Columbia University Press, 2002. Cardiff University. Is This What Killed the Dinosaurs New Evidence Supports Volcanic Eruption Theory. Chiappe, Luis M., and Lowell Dingus. Walking on Eggs. New York Simon amp...

Does Size Matter

This is another subject of great scientific debate. Some scientists say size matters. An investigation of extinction evidence shows that larger animals tended to become extinct more often than smaller animals. This could be related to the fact that larger animals tend to have smaller populations and do not have as many offspring. Larger animals also tend to live in a small geographical area. These facts would seem to make larger animals more susceptible to extinction. A species is more likely...

What Really Happened to the Dinosaurs

Earth Land Under Water

Without alarms, bells, or I screams, a giant asteroid races at 40,000 miles 64,000 kilometers per hour toward Earth. The asteroid, the length of more than 100 football fields, crashes near the Yucat n Pennisula in northern Mexico. The explosion is far greater than if every nuclear bomb in every country on the planet exploded at the same time. The meteor leaves a hole in the ground more than 150 miles 240 km wide. Its effects are immediate and devastating. The heat...