So, there’s this fossil fish from Kansas that has the brain – the actual brain, not the endocast – fossilized. There’s a LiveScience story about it.
The fossilized brain shows little connection with the shape of the braincase, which may force researchers to rethink earlier assumptions about the missing brains of previous specimens.
That’s not news – fish brains are long and skinny, with lots of bumpy projections; they don’t hew closely to the insides of skulls. I find fish brains interesting because of the odd cases that have really distinctive enlargements of one area or another. For instance, the buffalo fish has a large vagal lobe, which receives input from a unique sensory organ in the fish’s palate.
This fish has great big eyes. And:
The remarkably preserved fossil brain shows details such as a large vision lobe and optic nerve stretching to the proper place on the braincase, which fits with the fish's large eye sockets. But unlike typical ear canals that have three big loops to regulate orientation and balance, the ear canals of the extinct fish only exist on a horizontal plane. That meant the fish could detect only side to side movements, and not up or down.
They say they’re going to revisit other fossils from the Kansas-Oklahoma area. Hope they find some!