In late 1998 the first complete skeleton of a gorgonopsian was found in South Africa. We have to wait until the fossil is cleaned before we can assess the paleobiology of gorgonopsians better. Meanwhile, I don't know of a better account of gorgonopsians than a student senior undergraduate thesis by Alexandra Freeman . And it's not just the quality of this student paper. Hey, someone has to make all the rest of us look like underachievers.
Cynodonts are the therapsids from which mammals evolved.
Within cynodonts, the tritylodonts are even closer to the origin of mammals. Here is an image of the tritylodont Kayentatherium by Jack Conrad. Here is a picture of the skull of Estemmenosuchus . Dicynodonts were the first truly abundant worldwide herbivores. A dicynodont from Russia .