What is the Oldest Known Fossil?
The oldest know fossils date back to around 3.5 billion years ago. http://www.fossilmuseum.net/Tree_of_Life/Stromatolites.htm http://www.fossilmall.com/Science/About_Stromatolite.
The oldest known fossil is a stromatolite (meaning “mattress rock” in Greek) dating to 2.74 billion years ago. A stromatolite is a layered accretionary structure created when bacteria, especially photosynthetic cyanobacteria, trap layers of sediment between the biofilms they create. Stromalites come in variety of different shapes and sizes, including cones, columns, and branching types. For a long time, it was thought that stromatolites didn’t exist in the present (too many grazing organisms), until they were discovered in isolated, highly saline ecosystems such as Shark Bay and Lake Thetis in Australia and Cuatro Cienegas in Mexico. Like horseshoe crabs, because of their age, stromatolites are considered “living fossils.” The oldest known fossil of stromatolites is almost five times older than the oldest known fossil of a multicellular organism, which dates back to about 600 billion years ago. There are some even older stromalite-like formations dating even further back than 2.74 mill
