Step 6: Draw another curved, S- like line under the first one to complete the guide for the mosasaurus' tail. The tip of the tail should come to a point. The middle section should be thinner than the base and the section just before the tip.
Step 7: Draw a small U-shaped line that's tilted diagonally under the first circle as a guide for the front flipper. Add a smaller curved line to the right of it as a guide for the other front flipper. Draw another U-shaped line under the body on the right side near the base of the tail as a guide for the mosasaurus' hind flipper. Add a smaller curved line to the right as a guide for the hind flipper on the other side.
That's it for the initial sketch! From this point on, press harder with your pencil to get a more defined sketch.
Step 8: Draw a tiny circle near the middle of the arc at the top for the eye. Darken the sides of the circle to create the corner of the eyes and draw an even tiner dot in the middle for the pupil. Shade the inside of the mosasaurus' eye. Use a value that's ligther than the pupil. Draw a curved line close to the eye at the top and bottom for the eyelids. Draw a longer line above the eye for the thick brow. Add another line at the top to make the brow even thicker. Add a few more curved lines under the eye to give the dinosaur's skin more texture.
Step 9: Draw a series of V-shaped lines along the bottom part of the top arc for the row of teeth. Separate the mosasaurus' teeth a bit. Don't draw them all the way to the right side where the arc ends.