The Diplodocus's tail is made from two shapes. Draw one long triangle coming off the back and stretching almost to the edge of the picture. Overlapping the end of that shape, draw another, even skinnier shape that doubles back on the triangle. It should meet at a point at the end. For the legs on the far side of the body, start with a teardrop for the thigh of the back leg, an oval for the shin, and a rounded triangle for the foot. Draw a fat boomerang shape for the front leg and another rounded triangle for the foot. The Diplodocus is lifting this leg off the ground, so make sure it is not as long as the other front leg.
We'll add the muscle detail on the next page.