Arthropod trace fossils

thumb|270px|right|Cruziana from the Devonian [[Brallier Formation or Harrell Formation.]]

Protichnites is an ichnogenus of trace fossil consisting of the imprints made by the walking activity of certain arthropods. It consists of two rows of tracks and a medial furrow between the two rows. This furrow, which may be broken, set at an angle, and of varying width and depth, is thought to be the result of the tail region contacting the substrate.

Rusophycus is an ichnogenus of trace fossil (fossil records of lifeforms' movement, rather than of the lifeforms themselves) allied to Cruziana. Rusophycus is the resting trace, recording the outline of the tracemaker; Cruziana is made when the organism moved. The sculpture of Rusophycus may reveal the approximate number of legs that the tracemaker had, although striations (scratchmarks) from a single leg may overlap or be repeated.