tracefossil

Trace fossil, or ichnofossil, is the fossilized record of biological activity rather than preserved body parts. Trace fossils document behavior such as locomotion, feeding, dwelling, and reproduction. Common examples include burrows and borings in sediment or rock, trackways and footprints, feeding marks on surfaces, scratch marks, nests, and resting traces.

Formation and preservation depend on the interaction between an organism and its substrate. A trace forms when activity leaves an impression or construct that is subsequently buried and mineralized. The same trace can reflect different behaviors, and preservation is influenced by sediment type, burial rate, and diagenesis. Many trace fossils occur in soft, fine-grained sediments and in shallow-water settings, but traces are found in a wide range of environments and depths.

Classification and interpretation are the focus of ichnology. Trace fossils are classified by the morphology of the trace, not by the organism that produced it, leading to ichnotaxa such as Skolithos (vertical burrows), Cruziana (arthropod feeding traces in marine sands), Diplichnites (trackways of arthropods), and Gordia (meandering burrows). These traces help scientists infer paleoenvironments, behavior, sediment dynamics, and relative ages of rock units. They are especially valuable when body fossils are rare or absent, offering indirect evidence of ancient life and ecosystem structure. Limitations include ambiguity about the producer and the fact that similar traces can be formed by different organisms.