Prionochelys is an extinct genus of pancheloniid from the Mooreville Chalk and Eutaw Formations of Alabama. It consists of a single species, P. matutina.

Taxonomy

Prionochelys was originally assigned to the family Toxochelyidae. A 2018 paper found it to be on the stem of Chelonioidea, the family to which most modern sea turtles belong, forming a monophyletic grouping named as Ctenochelyidae with Ctenochelys and Peritresius. Below is a cladogram from the analysis by Gentry, Ebersole & Kiernan (2019):

Pan-Chelonioidea†Angolachelonia †Protostegidae †Toxochelys latiremis Chelonioidea †Ctenochelyidae †Asmodochelys parhami †Prionochelys matutina †Ctenochelys acris †Ctenochelys stenoporus †Peritresius ornatus †Peritresius martini
†Angolachelonia
†Protostegidae †Toxochelys latiremis Chelonioidea †Ctenochelyidae †Asmodochelys parhami †Prionochelys matutina †Ctenochelys acris †Ctenochelys stenoporus †Peritresius ornatus †Peritresius martini
†Protostegidae
†Toxochelys latiremis Chelonioidea †Ctenochelyidae †Asmodochelys parhami †Prionochelys matutina †Ctenochelys acris †Ctenochelys stenoporus †Peritresius ornatus †Peritresius martini
†Toxochelys latiremis
Chelonioidea †Ctenochelyidae †Asmodochelys parhami †Prionochelys matutina †Ctenochelys acris †Ctenochelys stenoporus †Peritresius ornatus †Peritresius martini
Chelonioidea
†Ctenochelyidae†Asmodochelys parhami †Prionochelys matutina †Ctenochelys acris †Ctenochelys stenoporus †Peritresius ornatus †Peritresius martini
†Asmodochelys parhami
†Prionochelys matutina †Ctenochelys acris †Ctenochelys stenoporus †Peritresius ornatus †Peritresius martini
†Prionochelys matutina
†Ctenochelys acris
†Ctenochelys stenoporus
†Peritresius ornatus
†Peritresius martini