The top page is fan-art/web-art for Man's Best Friend, a book for which I created cover art. This beastie is called a Kark and I think it's adorably terrifying. Oh btw, this particular Kark measures 25 ft in length, 10 ft at the crest of it's back, and 15 ft wide. ;D
The bottom page has some reference studies for the Kark.