Dunkleosteus Jaw Cast. Late Devonian (about 358–382 MYA). Many Dunkleosteus could grow to 11 metres (about 20 feet). Dunkleosteus had an enormous bite force of 6,000 N. They were part of the Arthrodire Placoderm fish genus. Dunkleosteus had an armoured exterior made of bone. Dunkleosteus Jaw Cast measures 42 cm x 15 cm.