Most Life on Earth Left No Fossil Record
Only a tiny fraction of species that ever lived became fossils, and an even smaller share has been found, leaving most of lifes history unknown.
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The fossil record is only a small window into the history of life on Earth. Most organisms that die never become fossils because fossilization requires unusual conditions, often including rapid burial and protection from decay, scavengers, erosion, and later geological destruction. Organisms with hard parts and those living in environments where burial is more likely have better odds of leaving evidence behind. Even after a fossil forms, it can remain buried, be destroyed by geological processes, or simply never be discovered. Scientists therefore know that the fossil record is highly incomplete and biased toward organisms and environments that preserve well. Estimates vary depending on how species and fossils are counted, but published estimates indicate that far less than one percent of all species that ever lived left a fossil record. This means the fossils scientists study are an important but very incomplete sample of ancient biodiversity. New discoveries continue to add pieces to the story, while countless species and details about ancient life may never be recovered.
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