Mark Witton, pterosaur-wrangler, Cthulhu-conjurer, globe-trotting paleo playboy and all-around scientific badass, drew this (and blogged about it): I liked it, but I thought it could use some color, so I hacked a crude version in GIMP and sent it to Mark with a, “Hey, please put this on a t-shirt so I can throw money at you” plea. Lo and behold, he did just that. You can get your own from Mark’s Zazzle store.