Ophiacodon was a large synapsid predator that lived during the Early Permian and competed for food with the likes of Dimetrodon. While it didn’t have a sail on its back it was clearly related in some way, a distant cousin to DImetrodon. It seems to have mostly preyed on fish and lived in or near water most of its life, but any animal nearly the size of a Komodo Dragon was not to be trifled with.