<span> rugged terrain
transportation
difficulties
I hope I help </span>
Answer:
Two possible reasons for the massive extinction at the end of the Paleozoic Era are an asteroid collision and massive volcanic eruptions.
Explanation:
The massive extinction that occurred at the end of the Paleozoic Era is the biggest extinction from what is known so far. The majority of the species died out, and whole families of animals and plants were wiped out of the face of the Earth. It was only small and highly adaptable organisms that managed to survive and give rise to the later life-forms.
The two possible reasons for this massive extinction are an asteroid impact and massive volcanic eruptions. An asteroid collision would have created drastic changes in a matter of minutes and hours, with effects lasting for a long period of time, thus eliminating the majority of the life. Massive volcanic eruptions, with the Siberian super-volcano being the prime candidate, may have caused enormous amounts of carbon dioxide and sulfur dioxide to end up in the atmosphere, thus rapidly changing the living conditions on the planet.
World War I and II. These wars caused lots of economic growth and development because there was a pressure to create better inventions. Having better technology could mean the win or lose of a war. :D
