DescriptionMiragaia was herbivorous, like all stegosaurs. It's closely related to the more famous Stegosaurus and Kentrosaurus. It had several plates that went down along its back, possibly for thermal regulating or attracting mates and scaring off rivals or predators. It had long spikes that came out of each shoulder, possibly for display. It also had several spikes on its tail (thagomizer) that it could use to hit predators with and scare off, if not injure or kill it. It was a quadruped, and walked around on four stout, slow-moving legs, but Miragaia was so well defended it didn't need to run fast. One feature that sets Mirigaia apart form other stegosaurs is its extended neck with 17 vertebrae in it. It travelled in herds containing juveniles, adults, and seniors. It grew to be about 20 ft (6 m) long from nose to tail, with the extended neck making up a lot of it. It lived alongside the sauropod
Deinhierosaurus, pterosaurs like Rhamphorhynchus, and predators like Ornitholestes, Torvosaurus, and Allosaurus. This represents the culmination of a trend of longer necks seen in stegosaurians. Additionally, Miragaia had more neck vertebrae than most sauropods, dinosaurs known for their long necks, which contrasts with the traditional view of stegosaurians as low browsers with short necks. Only the Chinese sauropods Euhelopus, Mamenchisaurus, and Omeisaurus had as many neck vertebrae as Miragaia, with most sauropods of the Late Jurassic possessing only 12 to 15. Mateus and colleagues suggested that the long neck either allowed Miragaia to browse at a level that other herbivores were not exploiting, or that the neck arose due to sexual selection.