Curator Galleries: #askacurator - Fossils

A fossil is the remains of an organism (plant or animal) that is preserved in rock.  The entire organism or only a small part of the organism can be preserved as a fossil.  Fossil remains can also be skin or body impressions of an organism or a trace left by an organism while preforming some activity, like walking, running, burrowing, or feeding.   Body fossils represent part or all of the body of an organism.  The hardest parts of an organism are usually preserved as a fossil, such as bones, teeth, shells, or the exoskeletons of insects or crabs.  The hard parts of an organism are most commonly fossilized, because they are the most heavily mineralized, making them resistant to weathering and destruction.  Think about how strong bones and teeth are compared to the soft, fleshy parts of a body, such as skin, muscles, or organs.  If the conditions are just right, the soft parts of an organism can be preserved in the fossil record, but this is very rare.  Hair, feathers, fingernails, and claws are not commonly found in the fossil record, because they are composed of a material called keratin, which isn’t as strong as bone, teeth, or shell.  Trace fossils are left behind while an organism is preforming some activity, such as tracks/trackways, burrows/borings, bite marks, or coprolites (fossil poop).  Trace fossils are important, because they provide information about the habits or behavior of an organism (how it moved, what it ate, or where it made its home).  Over 90% of all organisms never become a fossil.  An organism has a better chance of being fossilized if it is composed of a lot of hard parts, is very abundant, and lives in a lot of different habitats all over the world.  An organism is also more likely to become a fossil, if it gets buried under a lot of sediment quickly after it dies and it stays buried.  Even the hardest parts of an organisms will get quickly destroyed if they are left exposed to the weather or are allowed to be chewed on by other organisms.  The process of an organisms becoming fossilized typically happens very, very, slowly and will take 10,000s to 100,000s of years.