David Harold Blackwell ti a bi ni ojo kerindinlogun osu kerin odun 1919, ti o salaisi ni odun 2010 je Ojogbon ninu imo Statistiki ni ile-eko Yunifasity Kalifornia ni Berkeley, bee si ni oruko re wa lara awon aropojinle Rao-Blackwell.. 
The Base of the silurian is set at a major extinction event when 60% of Marine Species were wiped out.. 