Barbary lion skull from London

Workmen digging in the old moat around the Tower of London in 1937 were surprised to find two extraordinarily well-preserved lion skulls.

Using carbon dating, Museum scientists determined that one of the lions lived between 1420 and 1480. The other lived between 1280 and 1385, making it the oldest lion found in the UK since the extinction of wild cave lions during the last ice age.

Genetic testing on the skulls revealed that they were pure-bred Barbary lions, Panthera leo leo.

Pride of place

For centuries, the Tower of London was home to a royal menagerie of exotic animals, from polar bears to elephants.

Lions took pride of place at the Tower's entrance, fearsome gatekeepers serving as a symbol of the strength and nobility of the throne. But although they represented the majesty of the monarchy, it seems that these animals were probably malnourished and in poor physical health.

Reading the bones

Clues about the lions' diet and health can be seen on the younger skull.

• Vertebrates Collections Manager Richard Sabin describes the key features of the skull (BBC Radio 4 clip).

The hole where the spinal cord passes through the base of the skull to the brain is partially obstructed.

'You can make out that at the top of the hole there's an infilling of bone,' says Richard. 'It's actually a form of pathology. This is a reaction to, potentially, some sort of nutritional stress. As the infilling of bone grew it would have put pressure on to the spinal cord and possibly caused paralysis and blindness.'

Today, zoos keep their lions healthy by feeding them more complete diets of meat, which include hair, fat and bone. They receive all the nutrients they would get in the wild from eating the whole of their prey.

Missing majesty

Barbary lions originally roamed northern Africa, from Morocco to Egypt. But they were declared extinct in the wild in 1922, after centuries of over-exploitation and habitat destruction by humans.

Some people think it might be possible to bring Barbary lions back by selectively breeding captive animals thought to be descendants of Barbary lions. The question remains whether we should even if we could, particularly if their natural habitat couldn't support their reintroduction to the wild.

Instead, Richard believes we can learn a lesson from the Museum specimens:

'Humans decimated populations of Barbary lions and pushed them into extinction. The fact that we hold their remains in our Museum collections means researchers have the opportunity to extract scientific data and put them into a modern context, using them to look at closely related species that may be heading for extinction and potentially helping to slow or halt those extinctions.'