Central nervous system (display 85)

The disappearance of a species leads to the loss of information regarding its appearance, anatomy and behaviour. However, some clues can be recovered by studying the remains of the animal. Cranial endocasts are one example. Made from the cranial cavity, they can provide information on the cerebral anatomy of a species whose brain is no longer preserved. However, this technique is destructive: plaster is poured into the cranial cavity and, once set, is removed by sawing through the bone.

Thanks to advances in technology, non-destructive methods like x-ray micro-tomography can be employed. This high-resolution scanner makes it possible to see traces left by the brain on the inside of the cranium, without contact or damage. A digital model can then be generated from which measurements can be extracted and endocasts recreated with a 3D printer.

Bears

This cranial endocast is that of a cave bear, Ursus spelaeus. Distant ancestor of the brown bear, it became extinct about 27,000 years ago. Despite its imposing size (1.3 m tall at the shoulder, 3.5 m tall standing and about 500 kg), this animal had a small brain compared to that of certain modern bears. Cerebral volume is not directly linked to body size, which in this case is considerable because the animal had to store fat for hibernation.