The ranks are all named after the various Lizardmen units from 8th Edition warhammer. Your rank is dependent on your total post count, starting at a jungle swarm and finishing at a Slann (5000 posts). The spacing between ranks gets larger as you progress; so while you may need 10-20 posts to move up in rank when you start off, you'll need a couple of 100 later on, and about a thousand at the very highest tiers. The majority of the rank titles can be found between 0-1000 posts (Skinks, Kroxigors, Terradons, Troglodon, Razordon, Saurus, etc.). At 1000 posts you reach the level of Carnosaur and the following titles after that one are command ranks (Skink Chief, Skink Priest, Saurus Scar-Vet, Oldblood, Slann).
Well it kinda is, I got Slann of the first spawning, Since I was the first one to reach the Rank of Slann.
The big boss controls the list. He saved our forum from becoming a 404 error, so he has every right to it as far as I'm concerned I'm not sure I've seen the rankings list posted anywhere myself. I believe I was a Carnosaur until I hit 1500. Presumably I'll be a Scar-Vet at 2000. I think a Slann is at 5000? Skink Priest at 3000? Oldblood at 4000 perhaps.
Shouldn't Red devil be an old one?...uhh and a specific ranking, for the great artist, whom designed our awesome wallpaper! :-D