The client wants a image with sauroposeidon (the bigger brachisaur) making water sex, for explain that floating in the water can helps to avoid the weight problem. Personally I think this is a bad idea, because the male needs a strongpoint for elevate his body.

Maybe the answer is only a question of sexual sizes: if female sauropods are bigger than males, the weight problem isn't a big problem.

The sauroposeidon mesh is a lightwave morphed version of expressionimage camarasaur, a model cheap and useful. For scene, I compound a background picture with a 3d water displacement mesh.