Bad talk in the thagomicer range
While brumblestilts are the most abundant and iconic vertebrates of the coldvanna, the heaviest terrestrial animals in their habitat are not them, but a rodent called interglacial thagomicer (Flagellimus semiplantigradus), a one-ton beast equipped with a weaponized tail club. Despite its low profile, this mammal roams alone in its environment, primarily feeding on foliage and bark. While not as common as brumblestilts, they are ecologically fundamental species in the coldvanna biome, especially for maintaining semi-open environments in the hilly and mountainous regions of Antarctica, where brumblestilts are rare. Over the last million years, their appearance hasn't changed much, aside from their size growth and an increase in complexity of their tail club.
Like their ancestors, they possess digitigrade hindlimbs and plantigrade forelimbs, an adaptation for speed and digging under the soil or snow for food (during winter, over half of a thagomicer's diet consists of roots, low shrubs, and tubers). Despite their solitary behavior, thagomicers are highly social mammals that interact with other individuals of the same species and often seek protection in stottmice herds. While the protection provided by stottmice is not physical, as a single tail whip can be fatal for any predator in Antarctica, including a smoky beaster, thagomicers have poor eyesight compared to other giant rodents, putting them at risk of ambush attacks. By living together with other herds, they leave the role of sentry to other herbivores.
Spur shape and disposition of a thagomicer's club
This commensal behavior has transformed these brute-looking herbivores into mostly peaceful creatures towards other herbivorous animals, with which they often try to socialize. However, their pacifism fades when a predator appears. In such cases, thagomicers show their lunatic nature by standing their ground and using their club for intimidation; if this approach fails, they will directly attack the predator with their club.
Unlike the famous clubbed ankylosaurids (but like their jurassic ancestors), the tail of a thagomicer is highly flexible and can touch the head of the user to protect the frontal parts of the body, which is unarmed. However, this non-rigid yet heavy tail makes them susceptible to fast movements, sometimes resulting in vertebral dislocations and bone fractures. While thagomicers can heal from these injuries, the bones often badly fuse, causing some individuals to live with an inclined club that forms a 90° angle with the tail. Despite this, thagomicers are resilient, with sensory nerves less dense at the end of the tail, reducing pain reception.
To minimize damage to their main offensive weapon, these large rodents usually rely on their strong teeth in interspecific battles, which become more frequent during the breeding period.
