New University of Washington research indicates it is highly unlikely that comets have caused any mass extinctions or have been responsible for more than one minor extinction event. ... A long-period comet takes from 200 years to tens of millions of years to make a single orbit of the sun.

What are the 4 main causes of mass extinctions?

Mass extinctions happen because of climate change, asteroid impacts, massive volcanic eruptions or a combination of these causes.

What are the causes of mass extinctions?

What causes mass extinctions? Past mass extinctions were caused by extreme temperature changes, rising or falling sea levels and catastrophic, one-off events like a huge volcano erupting or an asteroid hitting Earth.