Tiny Ancient Fossils Provide First Glimpse of Organisms Eating Each Other

Posted on May 1, 2013

Gunflint chert fossil

Tiny 1,900 million-year-old fossils from rocks around Lake Superior, Canada captured ancient organisms eating each other. The fossils, preserved in Gunflint chert, capture ancient microbes feasting on a cyanobacterium-like fossil called Gunflintia. The fossil is pictured above and a 3D reconstruction of tubular Gunflintia fossils being eaten by heterotrophic bacteria (orange spheres and rod-shapes) is pictured below.

Gunflintia fossils being eaten by heterotrophic bacteria

The researchers analyzed the microscopic fossils (which range from 3 to 15 microns in diameter) using a variety of new techniques and found that one species - a tubular form thought to be the outer sheath of Gunflintia � was more perforated after death than other kinds, consistent with them having been eaten by bacteria. The researchers also say the findings indicate Earth would have smelled like rotten eggs 1,900 million years ago.

The research team was led by Dr. David Wacey of the University of Western Australia and Bergen University, Norway, and Professor Martin Brasier of Oxford University. The research is published here in Proceedings of the National Academy of Sciences.

Professor Brasier said in a statement, "What we call 'heterotrophy' is the same thing we do after dinner as the bacteria in our gut break down organic matter. Whilst there is chemical evidence suggesting that this mode of feeding dates back 3,500 million years, in this study for the first time we identify how it was happening and 'who was eating who'. In fact we've all experienced modern bacteria feeding in this way as that's where that 'rotten egg' whiff of hydrogen sulfide comes from in a blocked drain. So, rather surprisingly, we can say that life on earth 1,900 million years ago would have smelled a lot like rotten eggs."

Photos: David Wacey/University of Western Australia