Rusophycus (Early Ordovician ichnofossil) from the Mithaka Formation, Georgina Basin

Large trilobite resting traces (Rusophycus) from the Mithaka Formation are up to 30 cm or more in length, and are found in association with asaphid trilobites similar length. The portion of the Mithaka Formation in which the Rusophycus occur contains a rich fauna and ichnofauna, and is considered to have been deposited in very shallow-water marginal to wide intertidal harrier flats behind a sand harrier.