Mass Extinction
Written by Jerry Coffey
Mass extinction often refers to the theory that an asteroid, or a series of impacts, was responsible for the near extinction of all of the dinosaurs. It is known by several different names such as the D-T asteroid theory and the Alverez Asteroid Impact Theory. There are slight differences between these theories, but they all have the same basic premise: that an overwhelming event suddenly caused mass extinction of most of the life on Earth around 65 million years ago.
Some scientists theorize that one event could not have caused such wide spread death. It is their belief that a background of events were going on including some smaller impact events that had caused small scale die-offs. Most of these occurred during the Cretaceous period. The period was very active as far a tectonic shifting and volcanoes. Most of the super continents had separated and many of our current mountain chains were formed. Sea levels also rose significantly, causing widespread flooding and loss of land mass. The combination of all of these environmental changes may have caused a weakening of all species prior to the impact event at Chicxulub.
Many scientists believe that the event at Chicxulub caused the final stage of the mass extinction of 90% of the life on Earth. The Chicxulub Crater was formed by an impactor( either an asteroid or a comet) that was roughly 10 km in diameter and it hit with 100 million megatons of force. That is enough to make the atomic bombs dropped during WWII look like firecrackers. More than 50% of the worlds' species were killed off because of the climate changes caused by the dust that was thrown into the air. Nearly all of the dinosaurs eventually died from all of the changes that this impact event had on the Earth's environment. Acid rain and fires would have finished those that did not die from the initial impact.
Although mass extinction theories abound, they all center around a common theme: death from the skies. As the Earth evolved there were many traumatic climate changes that would have caused the death of thousands of animals. The ever changing Earth played a major part in the mass extinction of its early inhabitants. Will it do it again?
Here on Universe Today there are a few good articles about mass extinction. One covers the pace of recovering from a mass extinction and the other discusses the different extinction theories. Astronomy Cast offers and interesting episode on death from the skies.
Filed under: Astronomy
Related stories on Universe Today
- Recovering from a Mass Extinction is Slow Going
- Low Oxygen Accelerated the Great Dying
- Just a Single Asteroid Strike Wiped out the Dinosaurs
- Were the Dinosaurs Really Wiped Out by an Asteroid? Possibly Not (Update)
- More Evidence that Meteors Caused Mass Extinctions
