No, says Thomas Holtz in his new book, Dinosaurs. There’s a “space inside the hip vertebrae of Stegosaurus (and some other dinosaurs) where the spinal cord was contained [that] was very big. Some paleontologists … sugggested that this large space held an extra-large bundle of nerves. All vertebrates – including us – have these bundles, called ganglia, which help control the reflexes of the limbs and workings of the organs.
“In the 1990s, American paleontologist Emily Buchholtz examined the hips of living relatives of Stegosaurus (birds and crocodilians) and found that they also have an enlarged space in their vertebrae. But these animals don’t have an extra-large ganglion there. Instead, that space is filled with fatty tissue.”
Even if the extra-large ganglia had been there, Holtz says, it wouldn’t have been a brain equivalent.
Although perhaps the fatty tissue could be considered a brain equivalent in some.