Cat intelligence
The brain of the domesticated cat is about long, and weighs . If a typical cat is taken to be long with a weight of , then the brain would be at 0.91% of its total body mass, compared to 2.33% of total body mass in the average human. Within the encephalization quotient proposed by Jerison in 1973, values above 1 are classified big brained, while values lower than 1 are small brained. The domestic cat is attributed a value of between 1–1.71 relative to human value that is 7.44–7.8. The largest brains in the Felidae family are those of the tigers in Java and Bali, of which the largest relative brain size within the "panthera" is the "tigris". It is debated whether there exists a causal relationship between brain size and intelligence in vertebrates. Correlations have been shown between these factors in a number of experiments. However, correlation does not imply causation. Most experiments involving the relevance of brain size to intelligence hinge on the assumption that complex behavior requires a complex (and therefore intelligent) brain; however, this connection has not been consistently demonstrated.
Edmontosaurus
The brain of "Edmontosaurus" has been described in several papers and abstracts through the use of endocasts of the cavity where the brain had been. "E. annectens" and "E. regalis", as well as specimens not identified to species, have been studied in this way. The brain was not particularly large for an animal the size of "Edmontosaurus". The space holding it was only about a quarter of the length of the skull, and various endocasts have been measured as displacing to , which does not take into account that the brain may have occupied as little as 50% of the space of the endocast, the rest of the space being taken up by the dura mater surrounding the brain. For example, the brain of the specimen with the 374 millilitre endocast is estimated to have had a volume of . The brain was an elongate structure, and as with other non-mammals, there would have been no neocortex. Like "Stegosaurus", the neural canal was expanded in the hips, but not to the same degree: the endosacral space of "Stegosaurus" had 20 times the volume of its endocranial cast, whereas the endosacral space of "Edmontosaurus" was only 2.59 times larger in volume.