Rock Lords come in all shapes and sizes, but the ones that garner the most excitement are the ones that are weird. And let's be honest - they turn into rocks, they're all weird! Jawbone and his fellow Fossil Lords are weirder than most though - they are the Rock Lords combiner team! Not a lot of people know that there was a Rock Lords combiner - it was released late in the run, and only in Japan and parts of Europe in limited quantities. While the set was released in Europe as 'Fossilsaurus' it was released in Japan as 'Majin Robo Gattai Saurus' which roughly translates as 'Devil Robot Combining Dinosaur'. Which is hilarious.
Jawbone's articulation is limited. He can tilt his head up and down and his arms will move at the shoulders, though thanks to the rivet-cylinder design they tend to feel quite loose. His legs move at the hips though the joints are connected so they'll only move together, and while it looks like he has knees, they only bend forwards. The gun helps to break up the colour, but the hands don't grip it that tightly.