Models extracted from the prototype GonzagoGL, and showcased here. You can see the differenece in their height.
Interestingly, early creatures had functional fur/hair, something that the full release of Spore doesn't have.
Random assortment of models not used, but still floating around in the game.
Spore_Graphics.package/animations~/loading_placeholder_creature.rw4
Spore_Graphics.package/animations~/loading_placeholder_building.rw4
Spore_Graphics.package/animations~/loading_placeholder_tree.rw4
Spore_Graphics.package/animations~/loading_placeholder_ground_vehicle.rw4
Some of 3D placeholder models.