Both reptiles and our ancestor synapsids evolved from amphibians. While reptiles evolved better amniotic eggs, synapsid eggs were like amphibian eggs. Synapsid’s birthing process eventually led to mammalian live births. These are the animals that evolved Complex Sentience, the ability to feel various emotions. While it is unknown when this complex spectrum fully evolved, it is defined as the ability to suffer and feel the dichotomy of pleasure and pain. Dimetrodon is an example of a meat eater, which if any of our ancestors were meat eaters. Although not a While dimetrodons were not direct ancestor of mammals, our mammalian ancestors might have been similar to our direct-line ancestors around this time. 

Class: Synapsids (pre-mammal, not a dinosaur, not pre-dinosaur)
Evolution: Amphibians > Amniotes > Early Reptiles > Synapsids
Time Period: Late Triassic to Early Jurassic; 295-272 Mya; Diet: Carnivore