The Sculptures are excellent!
Is this just one mesh per dinosour?
With a one mesh setup without 3d-texture, the closest you can get is a prop.
Octane has no support for 3D-texture as of yet, so if you are going to do a organic creature you are going to do it old school if you are going to get it as realistic as possible.
Which means that you need meshes for muscles, bone, skin, organs, fat separately. The density of each group needs to be set individually.
The bad part about this, is that it will require ALLOT of render time and RAM.