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
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.