Perhaps Seraphitus is excess? In terms of the Seven Deadlies, Lust, Gluttony and Greed all come from excess, as treading on Pride, Envy, Sloth and Wrath might put him too close to the archdevils.
Perhaps Moriphractiel, being angel of Pangea, represents the removal of good and evil, the lack of moral absolute in a world without civilization. OR maybe he's just the angel of DINOSAURS!!!