Sudden changes in environmental conditions.
earth quake
Well because there is no proof.
in 2014
It is very likely that a comet has hit the earth in the distant past. It is possible that a comet striking the earth led to the extinction of the dinosaur.
A place where an earthquake has occurred in the past but not recently is known as a seismic gap.
false :)
Yes, extinctions have happened throughout history, they are happening today and will continue to happen in the future.
false
fossils
The rate of extinction is faster.
Every single extinction has happened in the past. If an extinction is happening this instant we will not know about it until it is in the past. As and when any future extinctions happen we will not know about it until it is in the past.
The past tense of "to occur" is occurred.
The past participle is occurred.
Yes, it is simple past tense.
The past tense is occurred.
The past tense of "occur" is "occurred."
The past participle of the verb "occur" is "occurred."