Step 15: Darken the outer edges of the initial guides to create the shape of the iguanodon's body. Use a wavy line when you darken the shape at the top for a bumpy texture on the back. Don't overlap the limbs that are on this side of the body as you darken the underside of the dinosaur's body.
Step 16: Darken the long, horizontal line on the left side for the top edge of the iguanodon's tail. Below that, lightly sketch another long, curved, horizontal line for the lower edge of the tail. Make the base of the tail wide. When you get the shape of the dinosaur's tail right, darken the line.
Step 17: For a cleaner look, erase as much as you can of the initial guides. Don't worry about erasing all of the guides. It's okay to leave some behind. Re-draw any final sketch lines you may have accidentally erased.
Final Step: Add some shading to your iguanodon drawing to give the figure more dimension and volume. Pick the direction of the light source when shading so that the shadows are consistent with it. Vary the pressure on your pencil to get different degrees of tonal value. For a more detailed guide on how to shade, check out this tutorial: How to shade.
Add more value throughout your iguanodon drawing for extra detail. Use a medium value for the rest of the body. Shade lightly at first, and then gradually build up to the level of darkness that's lighter than the shadows. Don't worry about shading too smoothly. The rough value gives the dinosaur's skin more texture. Use a dark value for the beak-like mouth and the nails. Leave a section blank on these parts for shine. Shading can be time-consuming, so be patient and take breaks.
Use a dark value to draw a series of pointy shapes on the body for a striped pattern on the skin. Nobody knows exactly what iguanodons looked like, so you can shade yours differently if you'd like. Add a few random scribbles across the dinosaur's body to give the skin a rougher texture. Add a cast shadow underneath. This helps to ground the dinosaur so it doesn't appear to be floating. Don't forget to pause the video after each step to draw at your own pace.