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Body fossil 2026-11-05
A body fossil preserves evidence of an organism's body or a part of it, such as a tooth, bone, shell or leaf. Preservation can retain original material, a mineralized structure, an impression or a cast. A body fossil therefore need not be an intact body or contain the original organic substances.
A trace fossil, such as a footprint or burrow, records activity rather than the body itself. Both are biological evidence, but they answer different questions: a tooth can constrain anatomy, whereas a trackway can constrain movement. Decay experiments show why preserved anatomy requires care: some characters disappear before others, biasing the apparent similarities used in phylogenetics.[ref]
Non-random decay of chordate characters causes bias in fossil interpretation by Robert S. Sansom and others. Experimental character-loss sequences and their consequences for fossil reconstruction
Fossil Created 2026-10-13 Updated 2026-11-05
A fossil is preserved evidence of past life in a geological context. A body fossil retains evidence of an organism's body, such as a tooth, bone or leaf; a trace fossil, such as a footprint or burrow, records activity. Complete replacement by minerals is not required for something to be a fossil.[ref]
What is a Fossil? by the National Park Service. Introduction and Definition
Fossilization can preserve different kinds of information. Permineralization fills spaces in biological material with minerals, while an impression may retain only external shape. These pathways help explain why the fossil record samples some anatomy characters much better than others, and why a transitional fossil is assessed through a combination of characters rather than overall resemblance.