At the time when this 3D model was created, it was very difficult to find BREP or NURBS 3D models of dolphins or other animals. Modeling such shapes is much more complex in NURBS 3D software than in polygonal mesh software. This is much easier to do today as more and more software (even cheaper ones) can convert polygonal meshes to NURBS surfaces.
One of the good things about the dolphin 3D model is that you can easily deform it to obtain various body positions. This is also how we got this dolphin 3D model, initially we drew it straight (stretched), and then folded the tail down. If you rotate it to the vertical, you will get the impression as if the dolphin is floating out of the water, and if you turn it down - as if it is diving into water. As you can see, by downloading this dolphin 3D model, you will obtain an initial 3D model from which you can create various 3D models, as well as their rendering and 3D animation.