New Species of Super-spined Hero Shrew Discovered

A new species of "hero shrew" -- a bizarre mammal with a remarkable lower spine -- has been found in Africa.

First discovered in 1910, hero shrews, also known as armored shrews, get their name for their super-strong spine, which has corrugated, interlocking vertebrae markedly different from any other mammal out there. While similarly sized mammals' spines typically account for no more than 1.6 percent of body mass, a hero shrew's accounts for 4 percent. The shrew's huge spine is capable of bearing huge amounts of weight, yet is still flexible. The shrew's super spine has long baffled scientists because it has no apparent adaptive significance.

"This shrew first came to light when explorers came to the eastern part of the Democratic Republic of Congo," said Bill Stanley, Director of Collections and zoologist at the Field Museum. "The explorers watched in amazement as a full-grown man stood on the back of the Hero Shrew, and the animal walked away, unharmed."

The new species of hero shrew, scientifically named Scutisorex thori, is the second hero shrew to be described in the scientific record. It bears much resemblance to the original hero shrew, but it is smaller, which has led Stanley and his colleagues to suggest it could represent an "intermediate between the original hero shrew and other shrews, since it possesses an interlocking spine, but with fewer lower vertebrae and lateral processes than the first hero shrew species."

While it measures less than a foot long and only weighs 1.7 ounces, the tiny shrew has a complicated spine.

"You and I have five lumbar vertebrae," said Stanley. "And so do most other mammals, but the [original] Hero Shrew at least 10. Scutisorex thori has eight vertebrae, and fewer lateral processes than the original species."

For the new hero shrew, the researchers suggest a novel hypothesis for the significance of the shrew's super spine: that it used the power and mass of the spine to ram into trees to gain access to otherwise inaccessible concentrations of beetle larvae living withing the wood. The animal might also use its hefty spine to lift logs or rocks in order to gain access to insects living underneath -- a food source that remains unavailable to many other mammals.

Stanley told BBC News that the new species might be a "missing link" to the evolutionary lineage of the shrew.

"The age of discovery is not over," he said, adding that, "This is just one example of a new mammal but there's still a lot more to this planet we have to learn about."

The new species will be used as a holotype, meaning it will be the basis from which all subsequent examples of the species will be compared.

A full scientific description of the new hero shrew is published in the journal Biology Letters.