  A ~ 62 My periodicity in fossil biodiversity has been observed in independent
studies of paleontology databases over ~0.5Gy. The period and phase of this
biodiversity cycle coincides with the oscillation of our solar system normal to
the galactic disk with an amplitude ~70 parsecs and a period ~64 My. Our Galaxy
is falling toward the Virgo cluster, forming a galactic shock at the north end
of our galaxy due to this motion, capable of accelerating particles and
exposing our galaxy's northern side to a higher flux of cosmic rays. These
high-energy particles strike the Earth's atmosphere initiating extensive air
showers, ionizing the atmosphere by producing charged secondary particles.
Secondary particles such as muons produced as a result of nuclear interactions
are able to reach the ground and enhance the biological radiation dose. Using a
Monte Carlo simulation package CORSIKA, we compute the biological dose
resulting from enhanced muon exposure from cosmic rays and discuss their
implications for terrestrial biodiversity variations.
