No, that´s just an useless idea against the Spinosaurus! Those monsters will break first one, and then the two fences. Only a electric fence will stop them; but in order to prevent them from frying themselves in the fence, you should use rocks and rock formations in a row to stop them.
Or sink the exhibit two tiles. This would work with all of the dinosaurs, just keep in mind that if you want to build hills in a T-Rex exhibit, you should place them in the middle of the exhibit, surrounded by trees, water and rocks. Or the T-Rex will just run over the fence.
Ah, another thing...don´t let the raptors´size fool you. Those tricky lizards can break through a concrete or iron bar fence used for holding even elephants...use an electric fence to keep them controlled. Or sink the exhibit two tiles and use a plexiglas fence; that would give an atractiveness boost.
And the plant-eaters can be kept in reinforced concrete fences, except for the Apatosaurus. It needs an electrified fence...but if you want it to look cool, or to remember the mucus-dinosaur scene in Jurassic Park, low the exhibit two tiles and use a low rock fence, surround it with trees (especially tropical ones) and look the results.
I hope this works for someone.