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When was the last time a comet hit earth and caused an extinction?
The Cretaceous Paleogene extinction event about 65 million years ago.
Is the Jurassic period a geologic time that followed the mass extinction of dinosaurs?
No. The Jurassic was in the middle of the dinosaurs' reign on Earth. The time period after the extinction of the dinosaurs is referred to as the Paleogene or the Tertiary.
Itmay have crashed into earth and caused a mass extinction a long time ago?
asteroid
Is that true The present rate of extinction is normal and about the same as at any other time in the history of the earth?
false
What signaled the end of the Paleozoic Era?
The Permian- Triassic extinction event was the greatest extinction on Earth. 95% of all organisms died during this time period, signaling the beginning of the Triassic.
How might the mass extinction at the end of the mesozoic era relate to the dominance of mammals in the Cenozoic era?
mass extinction: When at least 50 % of the species on Earth go extinct within a relatively short amount of time.
What ended the permian period?
The Permian Period was ended by the Permian/Triassic Extinction Event, which wiped out 90% of the species on Earth at that time.
What is it called in particular when a high percentage of the species on earth dies off at a particular time?
These are called "mass extinctions", and there have been five such events (that we know of) on the Earth. These are generally caused either by astronomical impact events (such as the asteroid that killed off the dinosaurs 65 million years ago) or massive volcanic activity. The causes of these extinctions has been a matter of some dispute, since they happened so long ago.
How many major extinction episodes has Earth seen in its time?
There have been five major extinction events on Earth, with the most well-known being the Permian-Triassic Extinction, often called the "Great Dying," which occurred around 252 million years ago and wiped out about 90% of marine species. The most recent major extinction event is the Cretaceous-Paleogene extinction, which occurred around 66 million years ago and led to the extinction of the dinosaurs.
What is the significance of the boundary between the cretaceous tertiary time periods?
The boundary marks the impact of a massive meteorite that caused mass extinction on Earth.
What is background extinctions?
A background extinction is the continuous extinction of individual species caused by climate change, disease, loss of habitat, and competitive disadvantages against other species. Background extinctions occur at a slow rate over time, affecting only a few species at one time.
What is the name for the modern era which began approximtely 65 million years ago with the mass extinction of the dinosaurs?
The modern era that began approximately 65 million years ago with the mass extinction of the dinosaurs is called the Cenozoic era. It is also known as the Age of Mammals, as mammals began to dominate the Earth during this time.
