Rusophycus

Rusophycus is an ichnogenus of trace fossil (fossil records of lifeforms' movement, rather than of the lifeforms themselves) allied to Cruziana.^[1] Rusophycus is the resting trace, recording the outline of the tracemaker; Cruziana is made when the organism moved.^[2] 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.

Rusophycus Temporal range: Early Cambrian–Early Triassic PreꞒ Ꞓ O S D C P T J K Pg N
Rusophycus trace fossil from the Ordovician of southern Ohio. Scale bar is 10 mm.
Trace fossil classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Ichnogenus:	†Rusophycus J. Hall, 1852

Both Rusophycus and Cruziana are typically associated with trilobites but can also be made by other arthropods.^[3] Rusophycus is known from sediments dating to the earliest Cambrian Period (somewhat before the first appearance trilobite fossils), and from the Triassic Period (after the Permian extinction of trilobites), indicating that other producers could make the trace.^[4]