Life of running
The stottmouse

The expansion of open environments has profoundly changed the evolutionary trends of Antarctic herbivores. In the absence of hiding spots from predators, some species have evolved to become unassailable, such as the tramplerat, while medium-sized species have been compelled to develop characteristics conducive to running. One of the most notable examples of this trend is the stottmouse (Musungulatum australis), the most common mesoherbivore on the continent. This species directly descends from the cambiocenic running vole, from which it distinguishes itself primarily in locomotion: the stottmouse is a digitigrade species, walking on the ground using only its four toes instead of the entire foot.

The species possesses a body fully adapted for running in the vast open habitats of the coldvanna and, more recently, the tramplesteppe. The head is proportionately enormous compared to the body and possess two pairs of incisors and only two pairs of molars per jaw, with a trend towards lophodontia, a dentition suited for grinding abrasive plant fibers like grasses.
Although stottmice occasionally exhibit a degree of gregariousness, they are generally solitary for a significant part of their lives. However, due to their high population densities, intraspecific interactions are common and easily observable. This species displays very elusive behavior and rarely engages in combat with other individuals over territory or to defend against predators. In exceptional cases, stottmice can defend themselves using their incisors, which can inflict deep wounds in muscle tissues.

Despite their running abilities, stottmice partially retain the burrowing behavior of their ancestors. Each individual constructs a short underground tunnel, typically no longer than 3-4 meters, used for seeking shelter from the winter cold and to raise their offspring. The gestation period lasts approximately 120 days, after which usually two twins are born, rarely 1 or 3.
As suggested by their name, stottmice often exhibit a behavior similar to the stotting of ungulates, in which the animal jumps with all four feet off the ground. The powerful hind legs of stottmice allow for a strong propulsion that can launch them almost 3 meters high. The exact purpose of this behavior is still unknown, but it is believed to aid in locating their burrows, serve as a fitness display to attract mates, and deter predators.