Did Dinosaurs Really Have Brains in Their Tails?

Many people have wondered about the intelligence of dinosaurs, especially the large and carnivorous ones. Were they smart and if so, just how smart? It appears that most large dinosaurs would probably have been sitting at the back of the class wearing the classic dunce cap, which may make them look a bit less ferocious. Smaller dinosaurs, especially the raptor group, tended to have the largest brains, suggesting greater intelligence. Larger dinosaurs on the other hand, were, to put it nicely, a bit dim, though their brains certainly functioned well enough for years of survival.

In the early 20th century, while studying the anatomy of the stegosaurus, some scientists advanced the theory that at least some dinosaurs had brains in their tails. From stegosaurus, this theory was applied to other large dinosaurs, like the nonexistent brontosaurus (really apatosaurs or brachiosaurs). Scientists found evidence that stegosaurus had a cavity near the base of the tail that could have held a brain even larger than the one in a stegosaurus’ head.

Just as the name brontosaurus has stuck, the idea that some dinosaurs have brains in their tails has remained a persistent belief, especially by those who don’t keep current on dino research. The fact is, dinosaurs's brains weren't located in their tails. What was previously thought a second brain center, likely represented an accumulation of fat cells, and a large number of nerve cells that could help control lower body and tail movement. In a sense you could almost say dinosaurs had brains in their tails because of the high number of nerve cells. In reality, though, these don’t function as a second brain.

Further, the urban legend about brains only applied to a very small group of dinosaurs. Most dinosaurs didn’t have this lump of tissues and the nerve/tissue space is only present in a few of the larger dinosaurs, primarily stegosaurus, brachiosaurus, and apatosaurus. The theory is that large heavy tails needed a lot of nerve receptors and independent control so as not to throw the dinosaur off balance. If you’ve ever looked at the twitching of a cat’s tail, it does appear to have a mind of its own, and thus though the idea that dinosaurs have brains in their tails is not true, their tails may have had that same kind of seemingly independent movement associated with modern animals.

For lovers of dinosaurs, who grew up studying them one way, we’re in for big revelations as DNA research becomes more refined. Recently, scientists found matter on a raptor that may confirm these dinosaurs really did have feathers, leading credence to the “birds are dinosaurs” theory. Ostriches have the same type of nerve structure at the base of their tails, but then, so do several lizards. It’s interesting to speculate how dinosaur books and illustrations may look in another twenty years or so. Perhaps instead of seeing the lizard-like beasts with which we’re so familiar, we may actually be looking at a lot of Big Bird’s ancestors in years to come.