Mammals O Their Rise 2 Oxygen
Helped Mammals Grow Study Shows" fr om the AP, reports that mammals
who were once very tiny and inhabited the forest floor, grew larger due to increased
oxygen over millions of years. Scientists believe the amount of oxygen doubled
over 205 million years.
The researchers took samples from the sea floor and by measuring the amount
of carbon-13 in the samples determined to be millions of years old were able
to estimate the the amount of oxygen in the atmosphere at a particular time.
They found the atmosphere contained only 10 percent as much oxygen in dinosaur
times. Once they disappeared, supposedly after the earth was hit by an asteroid
or meteor, smaller forms of life had a greater opportunity to develop and emerge.
Given the relationship between green plants producing oxygen and using carbon
dioxide one might think that there had to be some sort of parallel growth in
green plants as well.