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

extant Extant 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 * Extant taxon, a taxon which is not extinct, ...

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 different fa ...

native to the

Democratic Republic of the Congo The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...

. It and its

sister species In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

, the

hero shrew The hero shrew (''Scutisorex somereni''), also known as the armored shrew, is a large shrew native to the Congo Basin of Africa. Its features are typical of a white-toothed shrew − short legs, slender snout, dense fur − except for a highly u ...

(''Scutisorex somereni''), are the only

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

species known to have interlocking

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...

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, biological, scientific journal published by the Royal Society. It focuses on the rapid publication of short high quality research articles, reviews and opinion pieces across the biological sciences. ''Biol ...

'' 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 also known as Cal Poly Humboldt, Humboldt or Cal Poly"Cal Poly" may also refer to California Polytechnic State University in San Luis Obispo, California or California State Polytechnic Universi ...

Vertebrate Museum, as well as referring to the Norse god

Thor Thor (; from non, Þórr ) is a prominent 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 groves ...

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