Claim: Sarcoprion, best known for its extremely bizarre tooth morphology compared to other species of sharks and their closest relatives, the chimaeras, is an extinct genus of the extinct family Helicoprionidae.
Evidence: Sarcoprion (from the Ancient Greek for "flesh saw") is an extinct genus of eugeneodontid holocephalids from the Permian of Greenland. Similar to other eugeneodontids such as Edestus and Helicoprion, it was best known for its extremely bizarre tooth morphology compared to other species of sharks and their closest relatives, the chimaeras. Chimaeras are cartilaginous fish in the order Chimaeriformes /kɪˈmɛrɪfɔːrmiːz/, known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last three names are not to be confused with rattails, Opisthoproctidae, or Siganidae, respectively.