Study Suggests Clay Paved the
Study Suggests Clay Paved the Way for Evolution of Complex Animals Roughly 550 million years ago the first complex animals, such as trilobites, appear in the fossil record. Many scientists have concluded that an increase in the amount of atmospheric oxygen was critical to the relatively sudden evolution of these animals. They knew that photosynthetic organisms had been producing oxygen for hundreds of millions of years. But what could have led to the apparently rapid accumulation of the stuff in the atmosphere was a mystery. Now a team of researchers argues that clay may have played a key role.
Geologist Martin Kennedy and his colleagues from the University of California in Riverside realized that clay minerals in marine sediments are responsible for trapping the organic carbon that would otherwise bond with highly reactive oxygen. Today such clay minerals form in soil when organisms such as microbes or fungi interact with tiny bits of weathered rock. The resultant clay then washes down to the sea and settles on the bottom, where the clay's chemical properties actively attract organic carbon and then absorb it. [Scientific American]
