The Skulls Exhibit at the California Academy of Sciences is in full swing. (The link above has visiting times and promotional information.) When I first went to this exhibit a few months ago, I hardly noticed the huge elephant skull at the entrance. (I ended up on that first visit being captivated by the reptile skulls which are quite fascinating to look at comparatively.) It was only on my third visit that I realized that elephants have a large nasal cavity which leaves a void in the center forehead of their skull, very close to the cranium.
An African Elephant skull, about 1.2 meters in height, on the right.
(Me on the left, 1.73 meters in height.)
An Asian Elephant skull (juvenile), about 0.25 meters in height.
Looking at the picture of the juvenile Asian Elephant, it appears that there is still cranial structure at the back of the nasal void, meaning that it would take a bit of work to get to the brain.
I took some more pictures:
Skull of Bison (American Buffalo)
Skull of rangifer tarandus in cutaway, showing small cranial vault
Similar to rangifer tarandus, red deer and elk are small brained.
The large, very thick hippopotamus and rhinoceros skulls, also on display, don't have the open nasal void structure of the elephant. Their brains appear to be more protected. The elephant seal has a nasal void, but the rear structure at the back of the nasal void looks quite solid compared to the elephant. The walrus and bear also have nasal voids. The giraffe has a large skull. I could not see a cutaway of the giraffe skull, so I am not sure about the brain size. Strangely enough, the beaver also appears to have a large brain for its size. I'll have to have a closer look at these on my next visit.
Looking around on the web, it appears that the average weight of an elephant brain is about 5kg. Only large whales have bigger brains.
The bison (American buffalo) has one of the largest brains of any ruminant.
So, if I were in the market for brains, which does appear to have been the case for some humans, among plentiful land animals, the elephant (and its immediate relatives) and larger brained ungulates such as the bison, would be at the top of my shopping list.
(showing background on the skulls at the Cal Academy)
Ray Bandar talks about the skulls.
Moe Flannery, Collections Manager at the Cal Academy talks about the skull collection.