I once remember reading (15 years ago) that dinosaurs had two brains. One for their head and another one for their digestive functions. What is the current opinion on this theory? Has more evidence become available?
It would appear that at one time it was thought that a "gap" in the skeleton of a Stegosaurus was a space for another brain. This is now thought to be a storage space for extra food.
Googling your question brings up a number of answers along these lines:
This is a myth based on comments about the stegosaurus from a paleontologist in the 1800s. How it managed to persist is really beyond all logical reason but for a time it somehow managed to be accepted enough by the mainstream that it was even taught in school! You can still find this ‘fact’ online- just another reminder not to believe everything you read on the internet. Dinosaurs did not have 2 brains. There is an enlarged space that is likely to have housed glycogen- a characteristic shared by many birds. There is also a possibility that this area simply housed increased muscle and nerve mass, as in other living creatures signifying there back limbs were stronger and used more often than their front. Either way-no 2nd brain here. Google dinosaur 2 brain myth for a quick jump to the Smithsonian, a reputable source covering the myth, it’s origins, pervasiveness, and both possibilities mentioned above. Cheers!