I start by detailing with brown in technical drawing pens (sadly for me, my favourites, Edding 1800s, are no longer in production - gutted!) then lay down base colours with Tria markers. After that I do the highlighting and colour detailing with colour pencils.
I painted one of these years ago for a bioillustration project, I got very excited when I recognized this guy. Looks amazing! You definitely did it more justice than I did (and made it a whole lot scarier!). When one of your favorite things is random obscure extinct marine predators you don't expect to see them around terribly often, or well illustrated when they are.
awesome I'd never thought I'd see such an obscure and very little known about prehistoric creature on DA's front page! This thing is freaking scary in a book I have it says they grew up to 25ft-30ft and they found sharks teeth embedded in its "skin" or bony hard head so it must have fought the sharks. I imagine its teeth to be like sharp broken stone and I guess it can't close its mouth all the way.