A new species of giant elephant-shrew regarded as a living fossil has been discovered in the remote mountains of East Africa.

It is the biggest elephant-shrew in the world and is up to 50 per cent heavier and 20 per cent longer than any other species, despite weighing less than a bag of sugar.

The grey-faced giant elephant-shrew, Rhynchocyon udzungwensis, bears the distinctive long and flexible snout of the other 15 species of elephant-shrew known to live only in Africa.

Giant elephant-shrews, of which only three other species exist, are called living fossils because their body shape has remained virtually unchanged for up to 23 million years.

The species was discovered in a forested region of the Udzungwa Mountains in Tanzania after cameras set up to photograph forest antelope captured fuzzy images of a mysterious mammal. An expedition was launched in 2006 and researchers succeeded in capturing five of the animals, one of them half-eaten by a bird of prey, and made forty sightings.

Galen Rathbun, known as “the elephant-shrew guy” because of his 30-year study of the creatures, described the find as one of the most exciting of his career. “There hasn’t been a totally new form of elephant-shrew – especially a giant elephant-shrew – for more than 125 years,” he said. He saw a giant grey-faced elephant-shrew for the first time after spending several days searching fruitlessly in constant rain. His spirits soared when a triumphant colleague brought a specimen into his tent in a pillow case.

“My heart sank at first because it was so heavy. I thought it must have been something else. But then I looked into the pillow case and it was unmistakeably a giant elephant-shrew.”

Researchers, who reported the findings in the Journal of Zoology, were astonished by the size of the giant elephant-shrews, which were found to have an average weight of 710g (1lb 9oz) and a mean body length of 56cm (22in). They were so big that the traps taken into the jungle by the researchers had to be discarded because they were too small. Four giant elephant-shrews were eventually caught with snares.

The species is so named because its snout looks like an elephant’s trunk. It was later realised, despite the animals’ diminutive size, that they are more closely related to elephants, aardvarks and sea cows than to shrews.

Insects are thought to make up the bulk, if not all, of the animals’ diet, which they feed upon by nosing through debris on the forest floor with their snouts.

“The nose is part of the feeding strategy,” said Dr Rathbun, of the California Academy of Sciences. “Once it’s found it flicks [the insect] into its mouth with its long tongue – like a little anteater.”

The giant elephant-shrew has a black bottom, a pale cream chin and chest and russet-orange flanks. The creature’s numbers are estimated at between 15,000 and 24,000 and they are thought to live at high altitudes in a forest region that covers 300km sq (116 square miles).

Little is known about their behaviour except that they sleep in nests dug into the ground lined with leaves and come out by day to eat insects.

The researchers included scientists from Oxford Brookes University and Anglia Ruskin University.

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