Thor's hero shrew (''Scutisorex thori'') is an

extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

species of

shrew Shrews ( family Soricidae) are small mole-like mammals classified in the order Eulipotyphla. True shrews are not to be confused with treeshrews, otter shrews, elephant shrews, West Indies shrews, or marsupial shrews, which belong to dif ...

native to the

Democratic Republic of the Congo The Democratic Republic of the Congo (DRC), also known as the DR Congo, Congo-Kinshasa, or simply the Congo (the last ambiguously also referring to the neighbouring Republic of the Congo), is a country in Central Africa. By land area, it is t ...

. It and its sister species, the hero shrew (''Scutisorex somereni''), are the only

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

species known to have interlocking

vertebrae Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

Description

Thor's hero shrew has a smaller skull and fewer lower vertebrae—eight instead of ten or eleven—than its sister species. The vertebrae have fewer bony offshoots, and the animal's ribs are flatter and more robust. Like the hero shrew, it has an extremely strong back—roughly four times stronger than a human's, adjusted for size. It is less than long and weighs approximately . Hero shrews are generally less flexible than most mammals, but are able to turn around in confined spaces by sagittally flexing their spines.

Discovery

Thor's hero shrew was first described in ''

Biology Letters ''Biology Letters'' is a peer-reviewed scientific journal published by the Royal Society, established in 2005. It focuses on the rapid publication of short research articles, reviews, and opinion pieces across the biological sciences. The editor-in ...

'' by a team headed by vertebrate biologist William Stanley. In July 2013. It was discovered when Stanley dissected a specimen of hero shrew collected in the village of Baleko and found that its spine was different from those of known specimens. The team named the shrew after Thorvald "Thor" Holmes Jr of the

Humboldt State University California State Polytechnic University, Humboldt (Cal Poly Humboldt or Humboldt) is a public university in Arcata, California. It is one of Cal Poly (disambiguation), three polytechnic universities in the California State University (CSU) sys ...

Vertebrate Museum, as well as referring to the Norse god

Thor Thor (from ) is a prominent list of thunder gods, god in Germanic paganism. In Norse mythology, he is a hammer-wielding æsir, god associated with lightning, thunder, storms, sacred trees and groves in Germanic paganism and mythology, sacred g ...

due to the god's association with strength.

Evolutionary significance

The structure of Thor's hero shrew's cranium and vertebrae suggest that it may be descended from an evolutionary intermediate between the hero shrew and other shrews. Its existence may help explain the evolution of the hero shrew which, Stanley explains, has historically been cited as an excellent example of

punctuated equilibrium In evolutionary biology, punctuated equilibrium (also called punctuated equilibria) is a Scientific theory, theory that proposes that once a species appears in the fossil record, the population will become stable, showing little evolution, evol ...

, a theory that holds that species sometimes evolve very rapidly in short periods of time after long periods of stability. The existence of an intermediate species hints at a more gradual or incremental evolution for the hero shrew's extreme specialization. Thor's hero shrew may also help explain the evolutionary advantage of interlocking vertebrae. The animal's discoverers hypothesize that both hero shrew species use their strong backs to push under logs or rocks to find worms or to crawl into the tight spaces between the trunk and the bases of palm leaves to find larvae. The proposed behavior has not been observed in the wild, but the shrews are commonly seen in palm forests, where they have runways around the tree trunks.

References

{{Taxonbar, from=Q14283406 Mammals described in 2013 Scutisorex White-toothed shrews Endemic fauna of the Democratic Republic of the Congo