Pristerognathus was a medium sized therocephalian from the end of the middle Permian Period in the Capitanian stage, South Africa. It was a carnivore that more than likely was the kind of animal that would wait in trees or high rocks then would jump onto its prey and sink its huge fangs into the arteries in and around the prey's most vulnerable part- the neck. It was 1.5m long (4.9 feet) and it had a 25 cm skull which was very large proportional to its dimunitive size. It also had fearsome claws and could open its jaws very wide to take large bits for holding on.
It would have acted like leopards of today, running down its prey, suffocating it then dragging it to a safe place where no predators could get to its kill seeing it average size and inability fight off most of the large predators in its area. This means in no way that Pristerognathus was inept at killing and surviving in its extremely harsh world since it survived in it for a while in one of the hottest places on earth in one of the earth's hottest periods with all the large gorgonopsids were around. It might have been primarily a night hunter since it had large eyes and it would have been able to survive much better since night was a lot cooler, there were no predators around and its prey could not see it coming even if they had good night vision