The Deutsche Forschungsgemeinschaft (German Research Foundation) has spent three million euros to find out that saurpods glupped their food, thus allowing them to reach gigantic sizes.Chewing helps to digest the food faster. By the grinding process it is broken down and at the same time its surface is enlarged. This way the digestive enzymes are able to attack the food more easily.
'Chewing is a property of prototheria which no large herbivorous terrestrial mammal has got rid of,' Martin Sander says.
But chewing requires time – a resource that becomes scarce with increasing size. At the same time the following is true: the ones that chew need a large head, since molars and muscles have to be put somewhere. Not without reason elephants are quite big-headed. link