Shark week is almost here!! I just love those shows - the earliest known sharks date back more than 420 million years.
Wow that's really old? Have sharks changed much in that time?
eugenedontidans.
Under this broader definition, the earliest known sharks date back to more than 420 million years ago. Acanthodians are often referred to as "spiny sharks"; though they are not part of Chondrichthyes proper, they are a paraphyletic assemblage leading to cartilaginous fish as a whole. Since then, sharks have diversified into over 500 species. They range in size from the small dwarf lanternshark ("Etmopterus perryi"), a deep sea species of only in length, to the whale shark ("Rhincodon typus"
Gogoselachus
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.
Description.
"Gogoselachus" was a