Gogoselachus ("shark from the Gogo Formation") is an extinct genus of cartilaginous fish known from the late Devonian of Australia.
It is one of the earliest well-preserved Devonian chondrichthyans (20 million years older than Cladoselache), as much more of the fish than just teeth and scales were preserved.
This rare preservation reveals some unique discoveries about the evolution of the cartilage that was inside later cartilaginous fish such as sharks, rays, and chimaeras.
The specimen was found inside a broken concretion, and was made up of the complete lower jaws, the shoulder blades, gill-arches, scales and teeth.
During the specimen's preparation (dissolving the surrounding limestone with acetic acid), the cartilaginous elements were released surprisingly quickly, meaning that the fish's skeleton was made up of a special kind of mineralized cartilage.