Around 50 million years ago, in contrast, oxygen levels in the atmosphere measured 23 percent--2 percent higher than today.
A million years ago, oxygen was higher
This is false. 50 millions years ago, not 1 million
( z1 have-degree :ARG1 ( z2 oxygen ) :ARG2 ( z3 high :ARG1 z2 ) :ARG3 ( z4 more ) :time ( z5 before :op ( z6 now ) :quant ( z7 temporal-quantity :quant 1000000 :unit ( z8 year ) ) ) )