- Trilobite Trackway (Cruziana)
- Mississippian Age
- Perry County Indiana
Cruziana is a trace fossil consisting of elongate, bilobed, approximately bilaterally symmetrical burrows, usually preserved along bedding planes, with a sculpture of repeated striations that are mostly oblique to the long dimension. Trace fossils can reveal many aspects of their makers’ behavior, and work on Cruziana has been extensive. The makers of Cruziana are mainly considered to have been trilobites but they may also have been made by other unidentified arthropods. In some cases, the burrow begins or ends with a resting trace, called Rusophycus, whose outline corresponds roughly to the outline of the tracemaker, and whose sculpture may reveal the approximate number of legs, although striations (scratchmarks) from a single leg may overlap or be repeated. If the trilobite sped up, ichnogenus Diplichnites may result. Several specimens of Cruziana are commonly found associated together at one sedimentary horizon, suggesting that they were made by groups of trilobites.