Step 6: Draw two lines that connect the circles in the middle to finish the guide for the torso. On the left side of the body, draw two lines as a guide for the plesiosaurus' tail. The base of the tail should be wide and the tip should be thin and pointy.
That's it for the guides! From this point on, press harder with your pencil for a more defined drawing.
Step 7: Inside the plesiosaurus' head, on the top, right side, draw a very small oval for the eye. On top of the eye, draw a short, sloping line for the thick brow. Inside the eye, in the middle, draw a tiny dot for the pupil. Draw a couple of short lines on the sides of the pupil for the plesiosaurus' actual eyeball. Under the eye, draw a curved line for a crease on the skin.
Step 8: Darken the small arc on the top, right side of the head for the top part of the plesiosaurus' open jaw. Stretch the bottom line to the left inside the head and past the eye for a wide mouth. Darken the lower edge of the initial small circle and the arc on the bottom to create the lower jaw. Stretch the top line of the arc inside the plesiosaurus' head to make the open mouth longer. Inside the top jaw, draw a small slit for the nostril. Curve the lines for the bottom jaw a bit more.
Step 9: Draw a series of tiny, triangular shapes along the edges of the open mouth for the plesiosaurus' sharp teeth. Space out the teeth; don't crowd them. Add a short line near the left side for the other side of the lower jaw. Draw a curved line above the eye to emphasize the thick brow. Darken the outer edges of the initial guides to create the shape of the plesiosaurus' head. Draw a couple of short lines within the shape to give the head more structure.