Priscomyzon riniensis is an extinct lamprey that lived some 360 million years ago during the Famennian (Late Devonian) in a marine or estuarine environment in South Africa.

They also have a sucker disc of cartilage surrounded by a soft lip and a central small mouth set about with simple hooked teeth.

They attach to the bodies of other vertebrates by suction, securing their grip with the hooked teeth, after which a rasped tongue scrapes a hole providing access to the host's softer tissues.

Lampreys have ancient origins, have endured for 360 million years and lived through four major extinction events - even so, their evolutionary history is obscure.

The exceptionally well-preserved fossil of P. riniensis is only 42 millimetres (1.7 in) long and reveals details of its fin, gill basket and mouth region.

During these upgrades Gess managed to obtain a large sample of rock blocks with the help of the road construction company, and worked intermittently on exposing their contents.

The locality and horizon is the Waterloo Farm, Grahamstown, South Africa; Witpoort Formation, Witteberg Group, Famennian, Late Devonian.