The relative size differences would matter too, but how do we know dinosaurs produced "a great deal more sensory information than the marmoset"? Are you saying larger sense organs take in more information? Then again, if marmosets are more social dinosaurs, the marmoset's brain must process that social complexity. Could a brain as big as your fingernail suffice to process all that data and encode the content in conscious form? Brains are necessary, but perhaps nature's broader creativity adds the missing ingredient. After all, that's what brains and sense organs tap into: godless, self-transforming nature.