One of the most important questions still in the early Story of Life is when and how eukaryotes evolved. Most biologists accept Lynn Margulis’ assertion that the eukaryotic cell evolved from a sybiotic relationship between various prokaryotic cells. What does the fossil record tell us? The oldest eukaryotic fossil is the multicellular alga, Grypania. Coiled Grypania is found as thin films of carbon in rocks as old as 2,100 Ma in Michigan and young specimens have been recovered from 1,100 Ma rocks in China.
Although Grypania is the oldest body fossil, the fossil record for eukaryotes has been extended back to 2,700 Ma with the recovery of eukaryotic biomarkers in ancient oil. All organisms are composed of hydrogen-carbon chain molecules. It is possible that these molecules, or biomarkers, can be preserved in the rock record after death. In fact, the current view is that biomarkers present the most reliable clues to evidence of life preserved in the rock record. This has serious implications for the search for fossil extraterrestrial life.
Quick Links to: Introduction Oldest Rocks on Earth Oldest Fossils Prokaryotes vs. Eukaryotes Oldest Eukaryotes Oxygenation of the Atmosphere Ediacaran Fauna Snowball Earth Oldest Skeletons Pre-Cambrian/Cambrian Boundary Links for more information
