Step 10: Draw a small circle for the eye on the top, right side of the initial circle, on the outside. Sketch it lightly at first. When you get the placement and size right, darken the lines. Inside the allosaurus' eye, draw a tiny dot for the pupil. Add a few curved lines around the eye to emphasize the structure and the skin.
Step 11: Draw the allosaurus' horn in front of the eye as an arc that's wavy and pointy. Sketch lightly at first to get the shape right, then darken the lines. This dinosaur's horns were small, so don't draw them to big. Add a similar shape to the left for the horn that's on the other side. Add a series of short lines within the shape to represent the bony texture.
Step 12: Use the initial lines as guides to draw the top part of the open mouth. Follow the basic path of the guide, but make the lines wavier as you darken them for a more organic look. The line for the mouth at the bottom should be even wavier, and it should stretch to the left inside the circle. On the top, right side, add a few lines for extra detail on the dinosaur's skin and a small slit for the nostril.
Step 13: Now use the shape at the bottom as a guide to draw the allosaurus' lower jaw. Follow the path of the guide but make the line a lot wavier as you darken the line. Add a curved line on the left for the powerful jaw and a line in the corner of the mouth for the attaching skin.
Step 14: Draw a series of V-shaped lines along the top of the mouth for the dinosaur's teeth. Vary the size of the teeth a bit so that they don't all look exactly the same size. Now add the bottom row of teeth using more triangle-like, pointy shapes.