Stegosaurus' Second Brain

For many years it was believed that Stegosaurus, which had a walnut-sized brain in its head, had a second brain in its tail that was responsible for "hindquarters" thinking.



In recent years, the idea of a second brain was discarded. A parallel was drawn between the "second brain" and similar structures in some living species.



Lately, however, the idea of the second brain as a sort of relay junction box has regained favor. If Stegosaurus had two brains, neither was particularly large or complex.