8.
Mass extinctions occurred 250 million years ago and 65 million years ago. According to some scientists, which of the following reasons caused both mass extinctions?
A new species was introduced into an established ecosystem.
The diversity in the gene pool decreased dramatically.
A large comet or asteroid hit the Earth.
The Earth’s oceans changed a few degrees in temperature.
1 answer
C. A large comet or asteroid hit the Earth.