Have you ever looked at a spine? Really looked at it? Simple drawings and photographs cannot capture how truly weird and wonderful it is to see a fish's spine literally in the flesh as you're eating it; although we like to think of spines as smooth and linear, they aren't. They're knobby bits of bone on a nerve cord which have cool things like fins, ribs, and spikes sticking out of them. Hell, several dinosaurs can be distinguished from the spine alone.
Wait. That looks like a Stegosaurus, but...what? Did a Hallucigenia get tacked onto its backside like some crazy prehistoric gryphon part? How did it end up with shoulder spikes that look like they belong on a Pokemon? Explain, science, explain!
Kentrosaurus (lit. "prickly lizard") evolved naturally as a small stegosaurian. "Small" means 15 feet/4.5 meters as an adult dinosaur. It was first found in modern Tanzania and lived in the Late Jurassic. If Jurassic Park (or whatever name a real dinosaur-themed amusement park would use) resurrected these guys, they would not try to eat us. Like all stegosaurians, they were herbivores.
Keen observers will realize that Kentrosaurus looks somehow off-balance. It's like the hind legs are too long and its forelegs are struggling to touch the ground. It's not your imagination - this dinosaur really does have more emphasis on its hindquarters. Given that those hindquarters are holding a long tail edged with pointy spikes, this cannot be a good thing.
(Well, OK, it's a good thing for Kentrosaurus.)
Since Kentro's tail had 40 caudal vertebrae (about the same as a modern crocodile), it was relatively flexible as far as giant reptilian tails go. That hip emphasis combined with this flexibility allowed Kentrosaurus to swing its tail with an amazingly good range for a stegosaurian. (Some sauropods supposedly used their own tails as whips; I can make no promises outside of Stegosauria.) In short, anything that messed with Kentro wound up with its head on a pike - or osteoderm. (Yes, those spikes have a name.) Ouch.
Kentrosaurus is what happens when nature is without an uber-species that wipes out herbivores for fun and profit. Y'know, as opposed to food. Hunting only for food apparently leads to twisted badassery.