Step 6: Under the big circle, draw a couple of short, angled lines as guides for the dimetrodon's front legs. Pay attention to how the lines bend, as this will indicate where the joints will be later on.
Step 7: Draw two more angled lines under the circle on the right as guides for the hind legs. Again, notice how and where the lines bend so that you know where the dimetrodon's joints will be later.
Step 8: Add the guide for the dimetrodon's sail by first making a mark high above the body. Now draw a long, curved line from the neck to the mark. Sketch lightly so that it's easy to erase if you make a mistake. Now add another long, curved line on the right to complete the arc and guide for the sail.
That's it for the guides! From this point on, press harder with your pencil for a more defined drawing.
Step 9: Inside the head, near the top, lightly sketch a small circle for the dimetrodon's eye. When you get the size and position right, darken the lines but make the sides pointier and darker. Draw a couple of curved lines above and below the dimetrodon's eye for eyelids.